Inconvenient Facts

Here's something Donald Trump wishes you didn't know: nearly two-thirds of illegal immigrants remaining the United States annually do not cross the Mexican border (source here).

More than 700,000 undocumented immigrants are people who come to the US on a temporary visa and simply stay -- these are often called "overstays." In contrast, fewer than 400,000 undocumented immigrants cross the southern border without authorization.

Hence, Trump's proposed wall would do nothing to stop nearly two-thirds of undocumented immigrants.

Here's another inconvenient fact: anyone holding a Mexican passport can fly into Canada without a visa. The two countries have a mutual entry/exit pact much like the EU. And the US/Canadian border is very porous with no barriers and many backroad and backcountry crossings, primarily by Chinese nationals.

So if Trump's wall ever goes up, people from Mexico and Central America will simply book an ultracheap flight into Canada and then walk across the northern border. The number of illegal border crossings would drop but then overstays would spike.

This is why many Democrats and Republicans oppose Trump's wall -- it's wasteful to spend tens and perhaps even hundreds of billions on a plan doomed to fail.