The U.S. "border wall" is really a collection of walls, fences and other barriers that currently cover 652 miles of the 1,954-mile border with Mexico, according to the Government Accountability Office.
The wall is strongest along parts of the border that have large populations on both sides, such as San Diego and Tijuana.
Each city runs right up to the border, so Department of Homeland Security officials have built up double and triple layers of fencing for 14 miles starting in the Pacific Ocean and heading east.
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In other, more desolate parts of the border, there are only single fences or a variety of barriers, including iron vehicle barriers that people can easily walk past.
Most areas have no fencing, but some are nearly impossible to cross, from the widest sections of the Rio Grande to deep canyons and treacherous mountains.