If you really think any kind of wall will make an impact on drug availability you have a serious problem.
He's aware it won't:
But traffickers don't tend to send their products over the border along the places where Trump would build a wall, as Pacific Standard's Jack Herrera previously reported.
Instead, they mostly drive drugs over, in personal vehicles, through official ports of entry or Border Patrol checkpoints, as the Drug Enforcement Administration outlines in its National Drug Threat Assessment for 2017. Only a "small percentage" of heroin, for example, was seized along the U.S.–Mexico land border between ports of entry in 2017, the DEA reports. Heroin, cocaine, and methamphetamine were all most often found in personal vehicles, or tractor-trailers carrying legal goods, at ports of entry. U.S. officials also intercepted more than 200,000 pounds of cocaine as it was being shipped over the Pacific Ocean from South America, where it was produced, in 2017.
Fentanyl, the drug linked to the most overdose deaths in the U.S.—nearly 30,000 in 2017—mostly comes from Mexico and China. Traffickers drive it over from Mexico, again through ports of entry, or mail it from China.
These trends suggest that more resources for spotting drugs at ports of entry and in the postal system might help prevent some of these substances from entering the country, but that a more robust wall won't make much of a difference.
Naturally, he exaggerates the number of drug deaths (70,000 by the latest figures https://www.nbcnews.com/storyline/americas-heroin-epidemic/biggest-jump-drug-overdoses-was-among-middle-aged-women-n957211) and absurdly claims that every single one was caused by drugs crossing the border.