Jan Brewer was right. Most illegal immigrants were carrying drugs

In 2010, then Arizona Governor Jan Brewer took some heat for saying that a majority of illegals were drug mules.  

In fact, the numbers bear her out.  We can impute the number of drug carriers through the volumes of drugs seized by Border Patrol and estimated seizure rates; as well as the number of illegal border crossers arrested and assumed apprehension rates.  In 2010, for example, Border Patrol arrested 450,000 crossers representing 1.1 million crossing attempts for the year.  

In addition, Border Patrol seized 3.4 million lbs of drugs, virtually all marijuana.  We estimate interdiction rates at 14% (12-15% range), implying smugglers tried to bring in an astounding 23 - 29 million pounds of drugs over the border away from official points of entry in 2010.

Smuggler Percent.png

The standard backpack for drug smugglers is estimated at 40 lbs, thus 23 - 29 million pounds translates into roughly 1,700 - 2,200 smuggling trips per day.  Projected onto 1.1 m crossers implies that 51-64% of all crossers carried drugs in 2010. Thus, our mean estimates suggests that more than half of illegal border crossers smuggled drugs in 2010, just as Jan Brewer claimed.

As I have noted earlier, drug volumes seized by Border Patrol have been collapsing due to marijuana legalization in the US and, just recently, Canada.  Expected 2018 seizures of marijuana are forecast down 86% from 2009 levels, which would translate into 200-250 smuggling trips per day in 2018.  I'd note that these numbers do not entirely line up with anecdotal data from rancher Jim Chilton, with whom I had the pleasure of speaking last week.  Jim runs a 55,000 acre ranch of which 15 miles constitutes the border with Mexico.  Most of the crossers coming over his property appear to be carrying backpacks presumed to be filled with drugs.  If so, seizure rates may be substantially lower than believed in our analysis (and smuggling rates correspondingly higher).   

I would also add that drug mules are a combination of professionals -- who will make return trips -- and economic migrants, who carry drugs opportunistically one-time to pay their coyote fees.  By definition, the share of economic migrants carrying drugs will be lower than the total percentage of smugglers in all crossers. Notwithstanding, our current estimates still suggest that more than half of economic migrants carried drugs in 2010, falling to about 10% in 2018.

In any event, the marijuana smuggling business across the border is likely doomed and should fall to very low levels by the early to mid-2020s.