Saturday, January 23, 2010

Jon Baron has a new blog

Jonathan Baron's new blog, Judgment misguided, starts with a great post on Troubles understanding health-insurance reform. Read it, and you're likely to want to add it to your bookmarks, as I did.

He gives a quick quiz on the relevant economics to a web sample of Americans, and finds that indirect effects (let alone equilibrium adjustments of prices and behavior) are hard to understand.

Prostitution and the internet

Scott Cunningham and Todd Kendall have two papers on prostitution, which discuss among other things how sex is sold on the internet:

Prostitution, Technology and the Law: New Data and Directions” in Handbook on Family Law and Economics, Edward Elgar, Forthcoming 2010.

Sex for Sale: Online Commerce in the World’s Oldest Profession in Crime Online: Correlates, Causes and Controls, ed. Tom Holt, Carolina Academic Press, Forthcoming 2010.


Along with sites that offer sex for sale, there's been a growth in sites that offer customer reviews. E.g. PunterNet, a site that reviews British prostitutes (but is on a California computer) became briefly famous when a British politician announced that she would ask California's governator to shut it down: Terminate degrading site - Harman "Harriet Harman says she has asked California governor Arnold Schwarzenegger to shut down a website containing reviews of prostitutes."

Here's a paper on wages as a function of age for a similar website for US 'escort' services: The Wages of Sin by Lena Edlund, Joseph Engelberg and Christopher A. Parsons

Friday, January 22, 2010

Texas regulation watch: horse floaters and eyebrow threaders

The WSJ brings us the story: Texas Horse Dentists Feel the Bite Of State Regulatory Oversight

"For a quarter-century, Mr. Mitz has practiced the obscure art of horse-teeth floating. Using instruments roughened with diamond grit, he has filed down hundreds of thousands of equine teeth so that they don't grow into sharp points that can cut the horses' cheeks or throw off their chewing rhythms."...

"Veterinary oversight boards in Texas and several other states have moved aggressively in recent years to rein in unlicensed floaters, ordering them to stop practicing or to work only under supervision of a licensed vet."


The horse floaters have a legal champion helping them defend themselves.

""We want to vindicate our clients' constitutional right to float horse teeth without arbitrary and unfair interference," says Clark Neily, a senior attorney with the Institute for Justice, a nonprofit libertarian law firm on a mission to block state governments from overregulating.
In Texas alone, the institute is fighting on behalf of eyebrow threaders (who use cotton thread to remove unwanted facial hair), wig servicers (who fit and style fake locks), equine massage therapists, interior designers, locksmiths and karate instructors. The institute's clients argue that the state has imposed costly and unnecessary requirements for training or licensing.
Fifty years ago, just 3% of American workers were regulated or licensed by government agencies, according to the Institute for Justice. Today, it's 35%."


Here's a previous post concerning regulation and licensing in Texas (and elsewhere).

Progress towards a sensibly organized national kidney exchange

An important story has played out one more quite positive step in the dry prose of medical bureaucracy, in the form of a report of the Policy Oversight Committee of the Organ Procurement and Transplantation Network (OPTN) of the Health Resources and Services Administration (HRSA). (All of the reports are found here.)

The report in question is this one, OPTN/UNOS Policy Oversight Committee, Report to the Board of Directors, November 16-17, 2009, and the item in question has to do with how a pilot national kidney exchange might be organized, if it overcomes some hurdles presently standing in its way. In particular, the cumbersome review process is catching up with the progress being made in regional kidney exchanges, in which chains have become important, expecially since the introduction of Non-simultaneous kidney exchange chains .

"The Committee supports the Kidney Transplantation Committee’s proposal to include living donors and donor chains in the Kidney Paired Donation Pilot Program. (Item 3, Page 6)."

Here it is:

"3. Proposal to include non-directed living donors and donor chains in the Kidney Paired Donation Pilot Program.

Currently, the Kidney Paired Donation (KPD) Pilot Program only allows living donors with incompatible potential recipients to participate. Non-directed (or altruistic) living donors (those who are not linked to an incompatible potential recipient) have no way to enter the program. Also, candidate / donor pairs can only be matched in groups of two or three, and all donor nephrectomies in the group must occur simultaneously. This proposal would allow non-directed living donors to participate in the KPD Pilot Program and add donor chains as an option in the system. A donor chain occurs when a non-directed living donor gives a kidney to a recipient whose living donor in turn gives a kidney to another recipient and continues the chain. This proposal would allow two types of donor chains: open and closed. Closed chains start with a non-directed living donor and end with a donation to a recipient on the deceased donor waiting list. Open chains start with a non-directed living donor and end with a bridge donor who will start another segment in the open chain. In open chains, the
bridge donor nephrectomy does not occur at the same time as the other living donor nephrectomies.
Donor chains have the potential to increase the number of transplants in a KPD system.
The Committee used the scorecard to assess this policy, and the proposal received an overall score of 23.5. The proposal received average score of greater than 2.3 in every category except patient safety and oversight, geographical equity, and operational effectiveness.
The Committee unanimously supported this proposal by a vote of 9 in favor, 0 opposed, and 0 abstentions."

Thursday, January 21, 2010

Two new matching papers from Cal Tech

Federico Echenique, emailing from the left coast, sends along links for two new papers:

1) "Aggregate Matchings," joint with SangMok Lee and Matt Shum.

An aggregate matching market is a matching market (M,W,>) in the usual sense, but where we imagine that the elements of M and W are "types" of men and women, and that there may be more than one agent of each type. You can then study "aggregate matchings." For example with 3 types of men and women, these are matrices like

2 3 0
0 1 3
0 0 2

where there are 5 men of type m_1; 2 are married to women of type w_1 and 3 are married to women of type w_2; and so on.

Aggregate matchings are interesting because matching data often comes in this form, and many empirical papers use aggregate matchings.

The focus of the paper is on the empirical implications of stability for aggregate matchings. We ask when there are preferences that make an aggregate matching stable. It turns out that one has to look at a graph defined by the matrix; it's a graph you can draw on the matrix where the vertexes are all the non-zero entries, and there is an edge between v and v' iff they lie on the same row or column. Then the matrix is rationalizable iff the graph does not have two connected cycles. We also look a the model with transfers, and find that rationalizability with transfers is equivalent to the absence of cycles.

In the paper we develop econometric techniques for estimating preference parameters from imposing stability. The techniques are based on a moment inequality we obtain from stability. We have an illustration with US marriage data.
A PDF is in:
http://www.hss.caltech.edu/~fede/wp/aggregate_matchings.pdf

2) "Clearinghouses For Two-Sided Matching: An Experimental Study," joint with Alistair Wilson and Leeat Yariv.

This is an experimental paper. We wanted to test the Gale-Shapley mechanism in the lab. We were worried about the effects of direct revelation on experimenter demand: if you give subjects a preference, and then you ask them to report their preference, then they may start thinking about the motives behind the study. So we have a design where subjects go through the steps of the algorithm, making offers and holding on to proposals. We also think this design makes it easier to map actions into outcomes, compared to the direct revealaion alternative.

The findings are: First, 48% of the observed match outcomes are fully stable.
Among those markets ending at a stable outcome, a large majority culminates in the best stable matching for the receiving-side. Second, contrary to the theory, participants on the receiving-side of the algorithm rarely truncate their true preferences. In fact, it is the proposers who do not make offers in order of their preference, frequently skipping potential partners. Third, market char- acteristics affect behavior and outcomes: both the cardinal representation and the span of the core influence whether outcomes are stable or close to stable, as well as the number of turns it takes markets to converge to the final outcome.
A PDF is in:
http://www.hss.caltech.edu/~fede/wp/ech_wilson_yariv.pdf

Mathoverflow.net

Mathoverflow.net is an internet site on which people can ask and answer math questions. It elicits a good deal of effort for free, in an Open Science, reputation-mediated way.

It has a reputation system, based on the votes "up" your questions and answers get. Other users can also reduce your reputation by 2 points, at a cost of 1 point to themselves, if they don't like your posts.

There's also a set of distinctions that users can earn, called badges.

HT: Aaron Roth

Wednesday, January 20, 2010

Peer review and markets for ideas, in law and science

Most scientific journals involve "peer review," where the peers in question are supposed to be experts on the subject of a particular submitted article. Because reviewers' time is scarce, the presumption is that a paper submitted to a peer reviewed journal is not currently being submitted anywhere else. The author submits the paper, and waits for a review (either a rejection, a revise-and-resubmit, or an acceptance). Depending on the field and the journal this can happen quickly, or (for economics journals) slowly.

Law Reviews are different. Authors submit to multiple journals simultaneously, and the papers are reviewed not by peers but by the third year law students who edit that year's edition of their law school's Review. And well-received authors don't get "acceptances" they get "offers" to publish, which typically have a short deadline, e.g. 24 hours. In that time they can contact one of the other law reviews to whom they have submitted the paper and try to get it accepted there.


For example, the submissions page of the University of Chicago Law Review has the following invitation to ask for an Expedited Review: "If you have received a formal offer of publication from another journal and would like to receive an expedited review by the University of Chicago Law Review, please contact us at lrarticles[at]law.uchicago.edu. When requesting an expedited review, please put "Expedite" as the subject of your email and include in the text:
1) The author name and title of your manuscript; 2) The name of the journal that has extended an offer to you; 3) The date that the offer expires; 4) The phone number or email address of a contact person at that journal;5) An electronic attachment of your article (plus C.V. or cover letter) to facilitate and accelerate the process. The University of Chicago Law Review will attempt to honor all requests for expedited review for which the above information is provided. ..."


But there is an experiment afoot to change the way law review articles are reviewed, and to try to have peer review while still allowing authors to submit to multiple journals simultaneously: Mainstream law review tries peer review

The idea is to have the reviews done first in a clearinghouse called the Peer Reviewed Scholarship Marketplace "The Peer Reviewed Scholarship Marketplace (“PRSM”), a consortium of student-edited legal journals, exists to provide student-editors with peer evaluations of legal-scholarship manuscripts and to assure the publication of quality articles. PRSM connects authors and journals with subject matter experts, who through their reviews provide editors with the information they need to make informed decisions regarding article selection. With PRSM, the future of legal-scholarship publishing has arrived."

"The Peer Reviewed Scholarship Marketplace (“PRSM”) began with the South Carolina Law Review’s Peer Review Pilot Program... Numerous authors submitted manuscripts to the South Carolina Law Review, and many other legal scholars and practitioners volunteered to serve as peer reviewers. Relying on the reviewers’ evaluations, the South Carolina Law Review chose three articles for publication in a special Peer Review Issue (Volume 60, Book 4). This special issue also featured a favorable foreword by Judge Richard A. Posner as well as an essay describing the South Carolina Law Review’s experience with peer review.
The Pilot Program’s success encouraged the creation of PRSM, a consortium of student-edited legal journals that believe that peer review can enhance the quality of the articles that journals select and ultimately publish. PRSM works much like the familiar manuscript submission vehicle ExpressO but with a peer review component. Authors submit their work exclusively to PRSM, whose administrators then arrange for double-blind peer review of each manuscript. After six weeks, PRSM members will receive a copy of the article with the reviews, which will assist the student-editors in publication decisions. As with ExpressO, members will make their own independent offers to authors, who are free to accept or decline. If an author is unsatisfied with all offers—or receives none after a designated date—he or she is free to resubmit his or her reviewed manuscript through ExpressO or another preferred vehicle.
PRSM thus benefits all parties: authors, reviewers, journals, and the legal community that relies on scholarship published in student-edited journals. All authors receive valuable feedback from their peers, and successfully placed authors further benefit from the “peer reviewed” certification of their published manuscripts. Reviewers are offered an opportunity to comment on new scholarship pertinent to their areas of expertise and thereby participate in the “gate-keeping” article selection process. Student-edited journals are given an additional tool to spot and select the most novel and valuable research for publication. Finally, PRSM’s peer review process produces higher quality scholarship for the legal community that reads and relies on the profession’s journals.
For more information about South Carolina Law Review’s experience with the Peer Review Pilot Program and creation of PRSM, go here."

Apparently law journals in the UK are more like economics journals than like American law reviews, in that authors can only submit to one journal at a time, and submissions are peer reviewed (see Comparative journal submission experiences by John Ip).


In the meantime, a peer-review holdout in the sciences is moving to peer review. The Proceedings of the National Academy of Science, the journal published by the honorific society from which it takes its name, had a tradition of allowing NAS members to "communicate" papers without a refereeing process. For some time now that has coexisted with a peer review process; some papers are reviewed, others simply communicated. Next year that will come to an end, and all papers will be reviewed: PNAS will eliminate Communicated submissions in July 2010.

The problem is that communicated papers were apparently of very uneven quality. (Some biologists I know claim that PNAS stands for "post-Science and Nature," as papers are only sent there after being rejected by those two other journals.) And while there is a very sensible scientific tradition of simply ignoring bad papers, some of the ones that appeared were apparently embarassing: Peer Review Failure?

Peer review is undoubtedly a part of the answer to the larger question about why journals persist at all given the growth of the internet: Why Hasn’t Scientific Publishing Been Disrupted Already?

Tuesday, January 19, 2010

Random allocation, preferences, and welfare: a fish story

Flying from Madrid to Boston on an Airbus with two aisles not long ago, two stewardesses proceeded in parallel down the aisles offering food. I asked for the fish, but the stewardess in my aisle was already out of fish. Speaking to her colleague in the other aisle, she ascertained that her colleague still had some fish. Rather than pass the fish across the (empty) seat between them, “my” stewardess told me that, if her colleague still had fish when she completed her aisle, then I could have it. (I chose the vegetable dish…)

We see similar issues when changes are discussed in how to allocate deceased-donor organs for transplants, or some other policy where there has been a previous decision on an order of allocation to randomly arriving agents. To have passed the fish across to me would have disadvantaged some passenger who, but for the demand for fish on my side of the plane, would have been able to eat fish…

Of course, assuming that on which side of the plane passengers are seated is random, the policy of allowing fish to be passed from side to side and not just from front to back would have the same ex-ante welfare properties. But, once the passengers are seated, any change in policy would likely help some passenger only by hurting another.

This kind of discussion comes up from time to time in the allocation of school places, as well as transplant organs.

Monday, January 18, 2010

Onur Kesten on discrete allocation

Onur Kesten of CMU has two recent papers that offer new views of old problems.


Kesten, Onur , Why do popular mechanisms lack efficiency in random environments?
Journal of Economic Theory, Volume: 144 Issue: 5 Pages: 2209-2226 SEP 2009

"We consider the problem of randomly assigning n indivisible objects to n agents. Recent research introduced a promising mechanism, the probabilistic serial that has superior efficiency properties than the most common real-life mechanism random priority. On the other hand, mechanisms based on Gale's celebrated top trading cycles method have long dominated the indivisible goods literature (with the exception of the present context) thanks to their outstanding efficiency features. We present an equivalence result between the three kinds of mechanisms, that may help better understand why efficiency differences among popular mechanisms might arise in random environments. This result also suggests that the probabilistic serial and the random priority mechanisms can be viewed as two top trading cycles based mechanisms that essentially differ in the initial conditions of the market before trading starts."


Kesten, Onur, "SCHOOL CHOICE WITH CONSENT, Quarterly Journal of Economics, forthcoming.

"An increasingly popular practice for student assignment to public schools in the U.S. is the use of school choice systems. The celebrated Gale-Shapley student-optimal stable mechanism (SOSM) has recently replaced two de.cient student assignment mechanisms that were in use in New York City and Boston. We provide theoretical evidence that the SOSM outcome may produce large welfare losses. Then we propose an e¢ ciency adjusted deferred acceptance mechanism (EADAM) that allows a student to consent to waive a certain priority that has no e¤ect on his assignment. Under EADAM a consenting student causes himself no harm, but may help many others bene.t as a consequence. We show that EADAM can recover any welfare losses due to SOSM while also preserving immunity against strategic behavior in a particular way. It is also possible to use EADAM to eliminate welfare losses due to randomly breaking ties in student priorities."

Sunday, January 17, 2010

Allocation of deceased donor livers

Ex-chief of transplant program indicted in cover-up of patient switch

"On Wednesday, a federal grand jury indicted the former director of the liver transplant program at St. Vincent Medical Center in Los Angeles, California, for allegedly lying about a liver accepted for one patient but transplanted instead into another patient who was lower on the waiting list."

Saturday, January 16, 2010

blue guitar

Market design lyrics:

"They said, 'You have a blue guitar,
You do not play things as they are.'

The man replied, 'Things as they are
Are changed upon the blue guitar.'"


Wallace Stevens, "The Man with the Blue Guitar"

Indian names for college sports teams

Some people find repugnant the once common use of Native American names for college sports teams, and the practice is in steep decline: Native American mascot controversy. Here's a 'man bites dog' story, however.

In Twist, Tribe Fights for College Nickname
"Sometime soon, the Fighting Sioux of the University of North Dakota were to be no more, another collegiate nickname dropped after being deemed hostile and abusive to American Indians.
Except that some members of the Spirit Lake Tribe, one of two groups of Sioux in the state, say they consider the nickname an honor and worry that abandoning it would send them one step closer to obscurity.
“When you hear them announce the name at the start of a hockey game, it gives you goose bumps,” said Frank Black Cloud, a tribal member. “They are putting us up on a pinnacle.”
And so, in a legal standoff that has turned some preconceptions upside down, North Dakota’s top state lawyers will be in court on Wednesday to oppose members of the Spirit Lake Tribe who have sued to preserve the Fighting Sioux name and logo, an image of an Indian in profile, feathers draping down."

It looks like the tide will be hard to turn however: Judge Throws Out Lawsuit Seeking to Preserve Fighting Sioux Mascot

Friday, January 15, 2010

Ken Rogoff on grandmasters and growth

My colleague Ken Rogoff writes about two subjects he knows as well as anyone: Grandmasters and Global Growth.

Drawing analogies from the great progress in chess playing computer programs, he conjectures that artificial intelligence will power a lot of economic growth in the coming decade. I'm a bit skeptical, if only because AI has been the coming thing for at least a few decades now (remember expert systems?).

Of course, this may be a quibble about the "I" in AI. Herb Simon used to complain that the goal posts were constantly being moved; whenever computers became good at something that used to be thought to require intelligence, then "intelligence" would just be redefined. In this regard, I've been impressed at the big strides that have recently been taken in cheap, fast computerized translation: it's still a long way from passing the Turing test, but you can now tell at least what a web page is about in a lot of languages.

We're already seeing a lot of growth of computer assisted markets of all sorts, including many clearinghouses of the kind I often write about when I write about market design generally, including some of the developments in this past year. So maybe Ken is right, and after we enjoy the economic growth, we can quibble about whether these computerized markets and products are really smart...

Update: the February 11, 2010 New York Review of Books has an article by Gary Kasparov, The Chess Master and the Computer that includes a discussion of human-computer teams, i.e. of computer-assisted chess.

Thursday, January 14, 2010

Ethics of test preparations--for kindergarten

Sharon Otterman in the NY Times reports: Tips for the Admissions Test ... to Kindergarten
"Test preparation has long been a big business catering to students taking SATs and admissions exams for law, medical and other graduate schools. But the new clientele is quite a bit younger: 3- and 4-year-olds whose parents hope that a little assistance — costing upward of $1,000 for several sessions — will help them win coveted spots in the city’s gifted and talented public kindergarten classes. "
...
Private schools warn that they will look negatively on children they suspect of being prepped for the tests they use to select students, like the Educational Records Bureau exam, or E.R.B., even though parents and admissions officers say it quietly takes place. (Bright Kids, for example, also offers E.R.B. tutoring.)
“It’s unethical,” said Dr. Elisabeth Krents, director of admissions at the Dalton School on the Upper East Side. “It completely negates the reason for giving the test, which is to provide a snapshot of their aptitudes, and it doesn’t correlate with their future success in school.”
No similar message, however, has come from the public schools. In fact, the city distributes 16 Olsat practice questions to “level the playing field,” said Anna Commitante, the head of gifted and talented programs for the city’s Department of Education."

Wednesday, January 13, 2010

Languages as marketplaces

Linguistics and Economics have something big in common, they both study things that human beings have built collectively. Like markets, languages mostly emerge out of lots of collective action, only rarely is there much scope for conscious design. A big exception (or a small one, depending on your point of view) is Esperanto, the hopeful artificial language that was intended to be independent of nations and nationalism.

The New Republic has an informative article about Esperanto's designer, L.L. Zamenhof , and the formative early years of the language: The amazing story of how Esperanto came to be.

Languages and their catchment areas seem like a fruitful area for more study by economists. Just as it is hard for new marketplaces to compete with large existing ones when there are network effects, it is hard for new languages to gain a foothold in the marketplaces that languages provide for their speakers, since the benefits of speaking a language depend so much on how many other people already speak it.

Tuesday, January 12, 2010

Medical marijuana laws

Laws about marijuana give a different window on repugnant transactions.

Jan 12: N.J. approves medical marijuana bill "The Legislature approved a bill yesterday that would make New Jersey the 14th state to allow chronically ill patients access to marijuana for medical reasons."...

"Chris Christie, a former federal prosecutor who is the incoming governor and a Republican, said he supported the concept of the bill but remained concerned that a loophole could lead to abuses.
A compromise bill was worked out after some lawmakers expressed similar concerns. For example, a provision allowing patients to grow marijuana was removed.
Driving while high would continue to be against the law.
The other states that permit medical use of marijuana are Alaska, California, Colorado, Hawaii, Maine, Michigan, Montana, Nevada, New Mexico, Oregon, Rhode Island, Vermont, and Washington."
...
"Gusciora said the legislation, titled the Compassionate Use Medical Marijuana Act, would be the nation’s strictest such law."

"Strict" isn't an adjective you often hear paired with "compassionate."

Same sex marriage; recent developments

Same sex marriage continues to provide a window on repugnant transactions, i.e. transactions some people think other people shouldn't engage in.

January 5: New Jersey makes last-minute bid for gay marriage "New Jersey's state Senate will vote on legalizing same-sex marriage this week, officials announced on Tuesday, in a race against the clock before a new governor who opposes the measure takes office."
January 9: Gay marriage in New Jersey, once a sure thing, became tracked for defeat "Thursday’s state Senate defeat of the controversial bill, considered a "slam dunk" to pass just a few months ago, also was a simple case of what happens in the bare-knuckle world of New Jersey politics."

January 8: Same-sex marriage law backed in Portugal's parliament "Portugal's parliament has passed a law to legalise same-sex marriage, but rejected proposals to allow homosexual couples to adopt.
The bill was approved with the support of the governing Socialist Party and other parties further to the left.
...The law has been fiercely opposed by conservatives in the Catholic country."

January 11: Pope says gay marriage threat to creation "Pope Benedict on Tuesday linked the Church's opposition to gay marriage to concern about the environment, suggesting that laws undermining "the differences between the sexes" were threats to creation."

January 12: Historic court battle decides legality of 'gay marriage' in America "Americans could be forced to accept the legality of “gay marriage” in all 50 states of the union, depending on the outcome of an historic federal court battle that began in California yesterday.
The hearing in San Francisco — which was supposed to have been shown on YouTube before a decision by the Supreme Court to block the video feed — comes after 52 per cent of Californians voted to ban same-sex unions in 2008 with a ballot named Proposition 8. "

Monday, January 11, 2010

Mortgages, "strategic default," and repugnance

Steve Leider writes:
I’ve noticed lately that a lot of people (both public intellectuals like Megan McCardle and Rod Dreher as well as [other people I know]) seem to be really affronted at stories of people who walk away from mortgages that they can afford the payments on for houses that are under water (“strategic defaults”). Everybody seems to feel that even though this option is legal under the mortgage contract that this is somehow dishonorable or immoral. It’s a bit different from repugnance because while both parties voluntarily agreed to the contractual rules that allow this at the start, the bank probably isn’t happy about it now – but it has something of the same flavor of deep emotional disapproval of the economic activities of others.

http://meganmcardle.theatlantic.com/archives/2009/12/the_new_breed_of_deadbeats.php
http://blog.beliefnet.com/roddreher/2010/01/mortaging-ones-personal-honor.html

But see also Roger Lowenstein in the NY Times: Walk Away From Your Mortgage!
Update: see also Dick Thaler: Underwater, but Will They Leave the Pool?

Money laundering

Illegal markets, like those for narcotics, can't so easily make use of all the financial services provided by banks and other intermediaries, without leaving a trail for police investigators. So we have the phenomenon of "money laundering," designed to move the proceeds from illegal markets into the financial system so that they can be redeployed and enjoyed.

In some cases, money laundering may involve cash-intensive businesses that can simply report more sales than they actually make, and so transfer illegal currency into taxable revenue and bank accounts. In some cases it may involve the purchase and resale of portable assets. The police work associated with tracing this kind of crime involves the tracing of assets by forensic accountants, and agreements among banking authorities.

But apparently, for the part of the drug trade that moves drugs into the U.S. from Mexico, the most cost efficient way to launder the cash receipts is to physically smuggle currency in bulk back into Mexico: Along U.S.-Mexico Border, a Torrent of Illicit Cash. "Although United States authorities seized $138 million last year, that amount pales in comparison to the $18 billion to $39 billion a year the Drug Enforcement Agency estimates is being smuggled to Mexico every year."

Once in Mexico, it is apparently easy to turn dirty money into clean money, e.g. simply by exchanging it for pesos at a foreign exchange dealer. "A good portion of that is pooled by foreign exchange businesses and then shipped back to United States banks in armored trucks, experts on money laundering said."

And new financial instruments show up faster than laws to deal with them: "In a new trend, some organized crime groups have taken to smuggling prepaid money cards rather than cash, law enforcement officials say. United States treasury officials are working to require prepaid cards loaded with more than $10,000 to fall under the same reporting requirements as cash. Right now, anybody can walk or drive across the border with the cards filled with more than $10,000, without breaking any laws. "

Apparently the same hidden compartments in cross border vehicles that move the drugs in one direction can move the currency in the other, and so finding drug cash is a lot like finding drugs, and uses the same drug-sniffing dogs.
"The dogs and their handlers also find money, since most of it has traces of narcotics embedded in its paper. Drugs and cash are often stored or transported in the same compartments. "

The drugs and dogs game has quite a bit of a cat and mouse flavor to it: "There is an entire cottage industry devoted to building secret compartments in vehicles. Often the compartments will not open unless the driver takes a series of actions like pumping the brakes and turning on the dome light and the radio simultaneously. "

It's enough to make you appreciate bank accounts, checks, and credit cards, despite all the difficulty and fees in getting money wired to or from American banks as compared to European ones.

Here's a Department of Justice page on money laundering that makes clear the difference between contraband interdiction of the kind done by the Drug Enforcement Agency and asset tracking of the kind done by the IRS and other agencies, by showing big piles of seized cash.