Is there a better solution instead of a U.S.-Mexico wall?

The border between the United States and Mexico is the busiest land border in the world and one of the longest, covering more than 1,950 miles from the Pacific Ocean to the Gulf of Mexico. Four U.S. States (California, Arizona, New Mexico, Texas) and six Mexican ones (Baja California, Sonora, Chihuahua, Coahuila, Nuevo León, Tamaulipas) have territory along it. The Rio Grande, which flows to the Gulf of Mexico, accounts for some 1,240 of those miles, while the land boundary cuts through terrain running the gamut from desert to mountains.

As of 2014, 653 miles of this border has been fenced at a cost of about $7 billion. A few dozen miles are reinforced with secondary and tertiary fencing. About half of the fencing is designed to prevent pedestrians from crossing through, while the other half just blocks vehicles. The U.S. Department of Homeland Security reports that the pedestrian fencing cost an average of $6.5 million per mile, and the vehicle fencing $1.7 million per mile.

Border wall construction slowed to a halt in recent years, due in no small part to a slew of obstacles to its construction. But border-wall chatter is spiking during the 2016 U.S. presidential race, with Republican nominee Donald Trump’s proposal to build a full wall along the southern border serving as a cornerstone of his candidacy.

AS/COA Online takes a look at what’s been built so far and what stands in the way of future construction.