The U.S. government has built fencing along roughly one-third of the 1,933-mile southern border with Mexico. The border state with the longest boundary—Texas, at about 1,241 miles—is covered by only 115 miles of fencing. But according to experts, physical barriers are only one component of border security, and Trump could encounter similar challenges to his predecessors in trying to construct a wall—or more likely, additional fencing—across complicated, unpredictable terrain.
See Where Fencing Has Yet to Be Built Along Mexican Border
