President Donald Trump on Wednesday moved to ban the entry of citizens of 12 countries into the U.S.Gregory Bull/The Associated Press

“Close the borders! Don’t let any of them in!” You’re meant to picture the leader shouting this into an old-style telephone in a smoke-filled room, then a cut to scenes of tollgates being lowered, armed sentries standing in watchtowers, rolls of razor wire being stretched across streets and airplanes turning back.

In reality, border closings and travel bans generally have the opposite of their intended effect, causing mass rushes to beat the ban and sharp increases in illegal migration.

There are effective ways to use policy to stop unwanted movements across the border – but this ain’t it.

In his order this week to ban entry to the United States by citizens of 12 countries, Donald Trump was ostensibly responding to a genuinely horrific hate crime committed against American Jews in Boulder, Col., the previous week, allegedly by an Egyptian man who grew up in Kuwait. So it is only one of the absurdities of his action that the list of countries on the travel ban does not include Egypt or Kuwait.

Rather, it bans a hodgepodge of countries, most in Africa, with little in common. Notably, several of the countries have refused his........

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