Wall prototypes sit on the US-Mexico border

Border wall prototypes stand in San Diego near the Mexico U.S. border, seen from Tijuana, Dec. 22, 2018. The U.S. federal government remains partially closed in a protracted standoff over President Donald Trump's demand for money to build a border wall wi

A border wall prototype stands in San Diego near the Mexico-U.S. border, seen from Tijuana, Mexico, Dec. 22, 2018.

A border wall prototype stands in San Diego near the Mexico-U.S. border, seen from Tijuana, Mexico, Dec. 22, 2018.

A border wall prototype stands in San Diego near the Mexico-U.S. border, seen from Tijuana, Mexico, Dec. 22, 2018.

A border wall prototype stands in San Diego near the Mexico-U.S. border, seen from Tijuana, Mexico, Dec. 22, 2018.

A border wall prototype stands in San Diego near the Mexico-U.S. border, seen from Tijuana, Mexico, Dec. 22, 2018.

A border wall prototype stands in San Diego near the Mexico-U.S. border, seen from Tijuana, Mexico, Dec. 22, 2018.

A border wall prototype stands in San Diego near the Mexico-U.S. border, seen from Tijuana, Mexico, Dec. 22, 2018.

A border wall prototype stands in San Diego near the Mexico-U.S. border, seen from Tijuana, Mexico, Dec. 22, 2018.