https://www.americanthinker.com/blog/2020/01/proopen_borders_advocates_blame_stronger_border_for_rising_drug_abuse.html
For many people, including President Trump, one of the main problems with a de facto open border has been the fact that our southern border became a highway for drug traffickers. However, those who don’t like Trump’s efforts to secure the border have a different take: Trump’s policies increase drug use.
No one denies that America’s southern border has been porous when it comes to drug trafficking. Even left-leaning Wikipedia concedes that:
Most of the U.S. imports of drugs come from Mexican drug cartels. In the United States, around 195 cities have been infiltrated by drug trafficking that originated in Mexico. An estimated $10bn of the Mexican drug cartel’s profits come from the United States, not only supplying the Mexican drug cartels with the profit necessary for survival, but also furthering America’s economic dependence on drugs. (Endnotes omitted.)
However, when Trump wanted to make the border less permeable, Democrats said that it couldn’t be done. Nothing would stop the flow of either illegal aliens or illegal drugs. For example, in January 2019, Vox insisted that “Trump’s wall won’t do anything about the opioid epidemic: Trump claims his wall will stop the flow of heroin and other illegal drugs from Mexico. He’s wrong.”