If someone is detained because they appear ill, a medical expert from the Centers for Disease Control and Prevention comes to the scene to check them and, if necessary, send them back over the border.

VOA: standard.2009.04.30

She remembers flying with him in his single-engine plane across the Iowa border to check out crops, even though he didn't own them.

FORBES: Magazine Article

"A lot of Americans come down to Mexico and check their brains at the border, " says Duane Christie, an owner of the Century 21 master franchise in Mexico.

FORBES: Magazine Article

The cards would be used to check work authorization both at the border and inside the country.

FORBES: Taking a Good Look at the "Red Card Solution"