One of the main arguments President Trump and others have cited in support of the border wall is drug smuggling. In the U.S., marijuana is the main drug that is transported through areas where the border wall would make a difference.

But according to a study by the Cato Institute, U.S. Customs and Border Patrol seizure figures show that the amount of marijuana coming into the country has been falling continuously since 2014, when individual states began legalization. In 2018, the average Border Patrol agent seized 78 percent less marijuana than in 2013.

That’s more than doubling the number of Border Patrol agents and building 600 miles of border fencing did between 2003 and 2009. Despite these measures as well as deploying various surveillance technologies, the rate of marijuana remained unchanged through 2013 at an average of 115 pounds per agent. The number only began falling once states started legalizing marijuana in 2014.

But it’s not just marijuana. The value of all drugs being seized along the border between ports of entry has fallen by 70 percent since 2013. That’s because most drug smuggling activity now occurs primarily at ports of entry – areas where the border wall would have no effect. At the points of entry, the average inspector made seizures up to three times more valuable than those made by Border Patrol agents.

That’s mostly due to the fact that there, it is harder drugs being smuggled. The average port inspector seized 36 times more heroin, 23 times more methamphetamine, 17 times more fentanyl, and 8 times more cocaine by weight than the average Border Patrol agent.

When you consider these trends, adding more Border Patrol agents, or building an expensive border wall seems like a waste of taxpayer dollars. Marijuana legalization has done more to reduce cross-border smuggling than doubling Border Patrol agents and construction of the border fence did between 2003 and 2009.