Author: chogan@directresearch.com

 

In the prior post I established some basic facts.

1:  We’re still running somewhere around 2M unsuccessful attempts at illegal immigration, per year, at the Mexican border.  This is about a third higher than the previous peaks in FY 1986 (1.6M, Reagan) and FY 2000 (1.6M, Clinton).

Source:  Ultimately, the data are from US DHS, but read the prior post to see what I had to do to generate a consistent timeseries, including COVID-based expulsions,.

2: There are no hard numbers on the count of successful attempts at illegal immigration, per year, at the Mexican border.  That’s the subject of this post.  How do they estimate the number of illegal immigrants successfully crossing the Mexican border?

3:  The Congress has been funding increased personnel, barriers, and tracking technology at this border for decades, and continues to do so today.  That includes 1986 legislation that doubled the size of border patrol staff, and 2006 legislation that authorized 700 miles of walls/fences.  In recent years, the Congress has been funding “border barrier construction” at the rate of about $1.5B/year.  I believe this funding is what Biden administration is using to patch a few of the worst known holes in the Mexican border, in Arizona.

Source:  DHS Border Barrier Funding, Updated January 29, 2020, Congressional Research Service
https://crsreports.congress.gov, R45888   NOTE that there’s a large pot of money not under the control of DHHS that is not accounted for in the recent-year data.  As of this writing, I don’t know what that’s being used for.

I recommend that CRS report, cited just above, because you can see how rational the border control strategy was, at least historically.  To nobody’s surprise, they called in experts from the DoD, and they focused the resources on the easiest/busiest illegal entry routes first (CRS report, op cit, page 2).

That $1.5B a year is in addition to the roughly $6B one-time transfer within the Department of Defense budget, attempted by then-President Trump, to various border security projects.  Of which, only about $2.1B in total is available to be spent, the rest being tied up due to the (ahem) unorthodox way in which the funds were allocated, in part, via a declaration of a National Emergency. (This, as of the 2019 CRS report cited below.)

If you want to know what the DoD has been up to, with the monies re-allocated via declaration of National Emergency, there’s a corresponding CRS report on that, as of 2019, but I couldn’t quite make out what has actually taken place under that funding (reference available on this web page).  Near as I can tell, at the time that report was written, seven sections of border fence/wall were were agreed-upon to be built under DoD funding authority. But it’s clear that funding it this way created a lot of legal and other messes, some of which have resulted in the majority of funds not being spendable for border security.

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Efforts by DHS to Estimate Southwest Border Security between Ports of Entry

Rather than re-invent the wheel and do my own research, I’m just going to summarize a 2017 report by the US DHS, with the title shown above (reference).  This is, in effect, a report by the Government, on the performance of the Government, so it’s not clear whether there are any explicit or implicit biases in the analysis.   If nothing else, it’s probably about as good a summary of the technical problem as you are likely to find.

This is a report done at the behest of the Congress, given the attention that then-President Trump was focusing on the Mexican border.  As described in the Report:

Congress has directed the Department to provide more detailed reporting on southwest border security. The Consolidated Appropriations Act, 2017 directs the Department to publish “metrics developed to measure the effectiveness of security between the ports of entry, including the methodology and data supporting the resulting measures."

To paraphrase, how good a job are you doing now, at preventing illegal immigration across that border, and how do you estimate that?

So this report is exactly what I’m looking for.

Total interdiction rate, including those who turn back after crossing the border:  Implied successful illegal immigration rate of about 30% per attempt.

 

The report spends a of time talking about deterrence.  That is, the people who don’t even try to cross illegally, because we’ve made it tough for them to do so.  Or who turn back, once they see US DHS personnel.  And similar.

For example, US Border Patrol (USBP) personnel count “turn-backs”, that is, estimates of the number of persons who cross the border into the U.S., but turn back and return to Mexico once they spot USBP personnel there.

The USBP also counts “got aways”, that is, individuals observed to have made it past border security.  Essentially, these are reported either by direct observation, or by noticing signs of passage and inferring the number of people involved.

From such counts, plus apprehensions, US DHS calculates a couple of “interdiction rates”, that is, the fraction of all persons attempting to cross, who get successfully turned back.  One of those rates relies solely on data that U.S. DHS personnel observe, and so excludes most of the successful illegal immigrants.  A second estimate of the interdiction rate includes some estimate of illegal immigrants who managed to evade US DHS.

In round numbers, by the end of the period, the US DHS estimate for the success rate at crossing the Mexican border is 30%.  The other 70% either turned back voluntarily when they spotted USBP, or they were caught.

(Note that you CANNOT multiply 30%, times the roughly 2 million illegal immigrants caught at the border each year, to estimate the number of illegal immigrants at about 600K per year.  That’s because the TIR above also includes a count of “turn backs”, who are persons who were NOT apprehended crossing the border.  Based on the above, the estimated number of illegal immigrants has to be higher than that.)

But that depends critically on the very last factor above — the estimated (successful) illegal entries.

How do they estimate that?

Survey data, including only apprehensions (not turn-backs), implied successful crossing rate 50% to 70% per attempt.

There are several long-running surveys of migrants where they ask how often they’ve tried to cross into the U.S., and how frequently they’ve gotten caught.  I cannot even imagine what the potential sampling bias issues are for such surveys.  All I can say is that this DHS report summarizes the results of three long-running academically-sponsored surveys as shown above:  Roughly a 30% to 50% chance of being apprehended on any on attempt at border crossing.

So those who were willing to be surveyed — on either side of the border — report getting caught a lot less frequently than the US DHS “TIR” methodology would suggest.

near-border Repeat offenders, the partial apprehension rate:  Implied successful illegal crossing rate of perhaps 50%.

A final method used by US DHS is to track people who were caught and released into Mexico. Guess how many are likely to try it again.  Then see how many they catch a second time.

Once caught, they record “biometric” information, which I guess is fingerprints, face scans, and similar.  (So that they know if they catch them again.)

They restrict their analysis solely to individuals who live near the border.

Using a survey-based estimate, they take a guess at the fraction of those folks who are likely to try to enter illegally again.

And then they count the number that they catch a second time.

That yields the Partial Apprehension Rate shown above.  Admittedly, these are folks who by definition have had some practice at crossing.  But also, by definition, weren’t particularly good at it.  So, FWIW, they estimate that about half of that population successfully immigrates illegally across the Mexican border, on their second attempt.  And they take that estimate — roughly 50% — as a reasonable guess for the overall rate of successful illegal immigration.

Conclusion

I could go on.  This report presents its own complex estimate of likely count of illegal immigrants, but I honestly didn’t follow the logic or the resulting numbers.

The only real bottom line is that the Mexican border is quite porous, and that successful illegal immigration occurs routinely.  You could quibble over just how large a fraction, but as a good working estimate, you’d be justified in guessing that about half the people who try it succeed.

Moreover, there’s no strong trend there.  The is maybe a little harder to cross now, compared to (say) 20 years ago.  But only a little.

We’re currently targeting a billion or two a year at building and reconstructing walls and fences along the border, adding other security measures, and so on.  I’m hardly an expert, but I’m not seeing anything on the plate right now that hasn’t been there for the past couple of decades.

In any case, given the history of this, I think the notion that we’re somehow going to seal that border air-tight strikes me as somewhat far-fetched. Or expensive beyond our willingness to pay, take your pick.

My prediction is that the current Congress — if it can be prodded into action — will do what prior Congresses have done.  Address the worst known points for illegal entry.  Place a few more patches on the existing system.  And wait for the problem to go away for another decade or so.

No matter how you slice it, the influx of a million destitute people a year, in those border states, has to be putting a strain on something.

Despite the rhetoric, some Federal money goes to support whatever-it-is that communities in border states have to spend more money on, in response.  And while illegal (undocumented) immigrants (migrants) are not eligible for (e.g.) Medicaid, the Feds do, in fact, give communities money to deal with the basic humanitarian issues of food and shelter.  (E.g., $290M, per this press release).  Allocated like so, to local charities in those states, showing just the first few listed alphabetically:

But if you read the fine print, none of that applies to successful illegal immigrants, those who got across the border without being apprehended.  Or are not claiming asylum.  And so on.  Those grants to local charities only apply to those who have been “processed” in some form, by immigration authorities.

So at present, there’s a large influx of very poor people, who are almost by definition outside of “the system” and are categorically ineligible for any type of direct Federal assistance.  For example, they can’t get food stamps (reference).  They are, effectively, un-people.

The only major exception is for children.  Even if their parents crossed the border illegally, in theory, the U.S. won’t allow them to starve.  I think.  And schools that take Federal funds have to enroll them.  I think.  Including free and reduced price lunches, if they are not too scared to apply for that.

And so, we have this weird situation in those border states.  Everybody with any sense realizes they’re getting a million or so people a year, currently mostly refugees from bad conditions in South and Central America.  Or just looking for a better life.  Who crossed the border illegally.  And it’s a fantasy to expect that to stop any time soon.  If ever.  But the Feds can’t do anything to ease the resulting strain on state and local governments, because that large population falls entirely outside of the law.

Everybody knows they’re there, somewhere.  Everybody can see that more are coming.  But nobody can help state and local governments deal with the bulk of the problem.  Because that million-a-year influx consists of people who have no legal standing.  And so we carry on, with policy-by-fantasy, or policy-by-turning-a-blind-eye.  Or no policy at all.

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Addendum:  Gross versus net, or missing the reverse flow.

Source:  Immigrationpolicy.org

Notice anything odd about the graph above?  If there’s this huge ongoing influx of illegal immigrants … why are all the curves flat?  Why isn’t the estimate of illegal alien U.S. residents rising?

What I’ve looked at so far is the gross inflow of illegal immigrants across the border.   The graph above looks at the net number of illegal aliens living here.  Assuming both estimates are reasonably close to correct, there has to be a pretty big outflow of illegal immigrants, back out of the U.S.

So, as a matter of logic, I’m missing a potentially large flow of people in my overall analysis of illegal immigration.  Some fraction of successful illegal immigrants — those who cross the border illegally, and end up settled somewhere away from the border — eventually cross back.  To get at net illegal immigration, I should, in theory, subtract out that flow.

(And there’s also some fraction of that population lost to illegal immigrants who are granted some form of amnesty, and so convert to legal status.  But there hasn’t been a large-scale amnesty program since Reagan, I think.  Maybe there was one under Clinton?  And then there are attempts to convert the ambiguous legal status of individuals who came here illegally as children but are now grown-up Americans — without legal residency status.)

Historically, there seems to have been a reasonably large reciprocal flow of Mexicans returning to Mexico, from the U.S.  In fact, since 2008, more Mexican nationals have left the U.S. than have entered, by some estimates.  (Or this NY Times article, if you prefer a human interest story to mere statistics.).

To that you’d have to add anybody deported from the interior of the U.S., as only those captured near the border are counted in apprehensions.  (And even there, I’m not sure of the status of long-term illegal residents of communities near the border, who end up being deported as illegal aliens).

By all accounts, if you followed the graph above for another couple of years, there would have likely been an uptick.  But not nearly as much as you might guess, purely from the estimated gross flow of illegal aliens across the border.

Thus, the final lesson for today is that the net growth in the illegal immigrant population in the U.S. is far less than the gross influx of illegal immigrants in any year.

It’s a slight mis-statement to put it this way, but our porous border is porous in both directions.

Addendum 2:  Overstays

Prior to (say) 2017 or so, the single largest source of new illegal U.S. residents every year was individuals who overstayed their visas.  They entered the U.S. legally as tourists, students, or workers, with a visa specifying a defined period of residence, or perhaps legal residence when accomplishing some defined task (e.g., a course of graduate study).  And then the U.S. has no record of their departure, prior to the expiration of that visa.

In the FY 2022 Overstay report, by US DHS, 3.67 percent of persons with such visas overstated their visa, resulting in about 850,000 persons who were, for some period of time, illegal residents of the U.S., because they overstayed their visas.

Aside from that one factoid, I gleaned nothing else useful from that overstay report.  It’s not clear to me how much of that is bookkeeping errors, how much is persons who overstayed by a few days, and so on.  How many eventually left.  And so on.

So it’s hard to make much out of that, except to say that prior to the latest increase in likely illegal immigration at the Mexican border, that was consistently the single largest category of annual “illegal immigration”.  Take that for what it’s worth.