In 1990, the total appropriation to the Immigration and Naturalization Service (INS), including for adjudication of applications, was $1.2 billion. By 2012, appropriations to the two Department of Homeland Security (DHS) enforcement agencies, Customs and Border Protection (CBP) and Immigration and Customs Enforcement (ICE), were a combined $17.6 billion. The $17.6 billion figure does not count large ticket DHS enforcement programs like US-VISIT or E-Verify, or the substantial enforcement costs of other federal agencies, or the federal court system or states and localities. According to an analysis by the Migration Policy Institute, the funding and staffing levels of CBP and ICE exceed the combined levels of the four major Department of Justice (DOJ) law enforcement agencies. CBP and ICE also receive 16 times more funding than the three main US labor standards enforcement entities. Earlier this month, the Arizona Republic reported that the United States has spent $106 billion on border enforcement over the last five years, and has doubled the number of Border Patrol agents to 21,394 over the last seven years.
The legislation now being debated in the US Senate (S. 744) provides for multi-billion funding increases in enforcement at the US-Mexico border. It would require around-the-clock surveillance and a 90 percent migrant “effectiveness” rate — defined as the percentage of migrants apprehended or turned back — across the entire border. The recent debate has been over whether this rate and other enforcement goals will trigger and potentially delay the onset of a legalization program, and whether the Administration or Congress will make this determination. Senator Robert Corker (R-TN) and Senator John Hoeven (R-ND) have introduced an amendment to S. 744 — which has been endorsed by several Gang of 8 members — that would double the number of Border Patrol agents, add an additional 350 miles of secure fencing and increase border surveillance, including by drones. These border enforcement increases to S. 744 would cost an additional $30 billion, monies taken from net “savings” that the Congressional Budget Office (CB) has determined would be generated by the bill. Sen. Lindsay Graham (R-GA) has reportedly boasted that the amendment has “practically militarized” the border and Sen. Corker has called the amendment “almost overkill.” The question arises: does the United States actually need to invest more in border security? It likely does not and certainly not at the levels provided for by the Corker/Hoeven amendment.
Migrant apprehensions — a proxy for illegal entries — are at levels last seen decades ago, although they have climbed modestly in recent months. According to the Arizona Republic, Border Patrol agents arrested (on average) 106 migrants per year in 2005. Last year, agents arrested 17 migrants on average. In the El Paso sector, 3.5 migrants were arrested per agent. This is not surprising, given the exponential increase in agents in recent years. Nor is it surprising that DHS has not seen the need to request additional Border Patrol agents. By contrast, there is a need for additional immigration officers at ports-of-entry. Parenthetically, the CBO asserted that net unauthorized immigration would be reduced by 25 percent under S. 744, but this claim cannot be sustained since net unauthorized immigration is now less than zero.
One argument for increasing Border Patrol funding is that illegal entries will increase significantly when the economy fully recovers. The corollary is that growth in the unauthorized population stopped after 2007 because of the economic crisis. Two theories are offered to support this assertion: 1) the financial crisis caused emigration of unauthorized immigrants to increase considerably; and 2) poor economic conditions caused the inflow of unauthorized immigrants to decline after 2007. In fact, the best available statistical evidence shows no detectable increase in foreign-born emigration in 2008-2009 compared to previous years. The population stopped growing because new entries into the unauthorized population —visa overstays and illegal border crossers — fell dramatically from 2000 to 2009. Unauthorized “entries” might have been very modestly reduced by the economic crisis, but Figure 1 shows that the decline in these entries was as steep in 2006 and 2007 as it was in 2008 and 2009.
Others argue in support of high, difficult-to-measure “effectiveness” rates based on the fallacy that two or three crossers elude detection for every one arrested. In fact, if three migrants had “gotten away” for every migrant arrested at the southern border since 1965 — not accounting for “circular” migration — the very last of the 113 million residents of Mexico would have crossed the border in 2005.
Robust border enforcement is essential. However, there are at least two major reasons for not adding substantial new resources now. First, an expanded temporary worker program (of the kind anticipated by S. 744) is a more cost-effective way to reduce attempted entries than increased border enforcement. As temporary workers arrive legally through the ports-of-entry, illegal entries will drop even more than they have in recent years. The Border Patrol, in turn, will be able to focus more of its resources on stopping criminals and potential security threats and on interdicting the flow of illegal drugs across the border.
Every increase in border enforcement has made it more difficult for unauthorized seasonal workers to return to their jobs in the United States after going home for visits or holidays. So increasingly, these workers have remained in the United States. According to an INS study in the late 1990s, as many as half of those apprehended trying to enter the United States illegally were not new migrants — they were just trying to return to their residences in the United States.
Before 1968, there was no numerical limit on immigration from Mexico (or the Western Hemisphere). Limiting legal migration from Mexico — while failing to establish a large-scale temporary worker program — changed a circular, mostly temporary, migration pattern into a flow that was north-bound and relatively more permanent. The unauthorized resident population from Mexico increased sharply after 1968 because the United States made it harder for migrants to circulate legally.
Previous estimates also raise the possibility that overstays from Mexico increase as border enforcement increases. In annual estimates derived by the INS from 1985 to 1992, Mexico was by far the leading country for overstays. From 1985 to 1992, total overstays in the United States were estimated to be about 269,000 per year. Of those, about 48,000 per year, or 18 percent, were from Mexico. Although no similar estimates have been made since 1992, the continuing buildup of border enforcement over the past two decades might have increased the annual number of overstays from Mexico. Additional increases in border enforcement are likely to yield diminishing returns at an increasing cost.
The discussion of border control raises the possibility that the additional border enforcement resources included in S.744 and in the Corker/Hoeven amendment could be unnecessary at best and counterproductive at worst. Any marginal additional gains in reducing illegal entries between the ports of entry could well be offset by increases in overstays as well as other methods of illegal entry, such as stowaways and entry with false documents.
Overstays dropped dramatically after 9/11, and as long as current levels of security remain in place illegal entries and overstays should remain at low levels. Figure 2 shows trends in total overstays from 2000 to 2009. Moreover, despite the assumptions in the recent CBO report, overstays in the new temporary worker programs in S. 744 are likely to be fewer than 10,000 per year, and probably well below that. INS estimates for 1985 to 1992 show that slightly over 2 percent of total non-immigrants overstayed each year; for Mexico, the rate was 5 percent. If rates have remained relatively constant, the annual number of overstays of 200,000 new temporary workers each year would be in the 5,000 to 10,000 range. Full implementation of the E-Verify program should further reduce the number of overstays.
 In addition to the steep decline in overstays and illegal entries from 2000 to 2009, the number leaving the unauthorized immigrant population, through emigration, removal by DHS, adjustment to legal status or death, increased gradually throughout the decade, exceeding a half million in 2009.