Five reasons why Trump's wall will only ever be a fantasy

4. Border barriers will not stop drugs or terrorists. This is so for two different reasons. First, building more fences will not stop drugs because drugs are extremely profitable. As long as the United States continues its tragically ineffective war on drugs, drug cartels will figure out ways to overcome any obstacle to get their product into the country.

“The only law that cartels do not break is the law of supply and demand,” explains Paul Kan at War on the Rocks. And “as new barriers along the border increase risks for the cartels,” he continues, “they will innovate smuggling operations, raise their prices to keep profits flowing, and stimulate new domestic markets in Mexico and on the U.S. side of the border.” They already did this “after 9/11, the last time the United States seriously tightened its border security,” Kan adds. They can do it again.

The second reason is that unfenced borderland is not the exclusive thoroughfare for drugs or terrorists. For example, the Trump administration’s own Drug Enforcement Agency has found the majority of heroin from Mexico enters the U.S. through legal ports of entry. Likewise, contrary the administration’s disingenuous suggestion that 4,000 suspected terrorists have been caught at the southern border, the apprehension of “non-U.S. persons” on the terrorist watchlist averages about one per month, and more are apprehended at our northern border with Canada.