Border control issues with Mexico boil down to smuggling in marijuana, 'hard drugs', and illegal immigrants.
Attempts to enforce bans on illegal immigrants and hard drugs have materially failed under President Trump. By contrast, the legalization and taxation of marijuana has succeeded in dramatically reducing smuggling of that drug.
Let's take these black markets in turn.
Hard drugs consist of principally of heroin, cocaine, methamphetamine and fentanyl. Policies associated with interdicting these drugs can only be described as an abject failure, with seizures up by half since President Trump took office, compared to the prior two fiscal years.
The vast majority of hard drugs come through Customs at official crossing points. Such contraband is almost impossible to detect, with our estimate of interdiction rates by weight around 3%. Seizures have been rising due to both supply and demand considerations. A strong economy brings with it demand for flashy drugs, most notably cocaine, which is rebounding in both the US and UK. In addition, drug traffickers have been trying to compensate for the collapse of the marijuana smuggling business. The rise of fentanyl may well be the result, as traffickers both look for new product and a way to increase the potency of their offerings at a lower cost. The hard drug scene is likely to get worse, and possibly much worse, for the rest of this business cycle.
Seizures of marijuana have dropped by nearly 60% since President Trump took office. By any reasonable measure, this should be considered a fantastic success and trumpeted as a key accomplishment of the Administration. Of course, declining volumes are due to marijuana legalization, most recently in Nevada, California and Canada. Marijuana smuggling across the border is rapidly coming to an end and should cease entirely if Texas decides to legalize cannabis. Whereas drug enforcement efforts have failed, legalize-and-tax has worked, and worked spectacularly well.
Illegal immigrants come to the US primarily in search of higher wages. The administration has attempted to curtail such immigration with enhanced enforcement. Numbers were down last year, but due principally to the 'Trump effect', which intimidated migrants from attempting to cross into the US. However, the impact has faded, and crossings have returned to more typical levels. Although enhanced enforcement has kept illegal immigration 10-15% below our expectations given the strength of the economy, such efforts have failed to move the needle in any more material way. An enforcement-based strategy is not bringing results.
Instead we should apply our successful strategy with marijuana to illegal immigration: legalize-and-tax. By implementing such an approach, we would effectively terminate illegal immigration and close the border by the early 2020s, without a wall or aggressive enforcement.