A U.S. Government Accountability Office (GAO) report released on September 7, covering harms done by Trump-era U.S.-Mexico border wall construction, includes the only number I’ve seen of the total amount of barriers currently built along the border.

A bit oddly, the report doesn’t exactly say how many miles are fenced off. But GAO reported that number in 2017, and last week’s report explains how many new and replacement miles got built during the Trump years. It’s easy to add them together.

20172023Difference% Difference
Pedestrian Barrier354636282+80%
Vehicle Barrier300105-195-65%
Total Border Fencing65474187+13%

Taking those sources together reveals that 741 miles of the U.S.-Mexico border is now fenced off.

Of that amount, 636 miles are fenced off with what usually gets called “border wall”: “pedestrian fencing,” or segments of barrier that are high enough, with slats close together enough, to block someone crossing on foot (and unwilling to climb). The other 105 miles are “vehicle fencing”: usually, barrier that is low or widely spaced enough to walk through or over, but not to drive through or over.

The Trump administration built 87 miles of border wall in spaces that had no barrier before. That doesn’t sound like much: a 13 percent increase over where things stood at the end of the Obama administration. But Trump’s people replaced 195 miles of vehicle fencing with pedestrian fencing, for a total of 282 miles of new pedestrian barrier: an 80 percent increase. And they made a lot of old pedestrian barrier taller, or double-layer.

The entire U.S.-Mexico border is about 1,950 miles long (it’s hard to measure exactly over all of the Rio Grande’s twists and turns). So today, about 38 percent of the U.S.-Mexico border is fenced off, 33 percent of it with pedestrian fencing. The Trump administration added new fencing over 4 percent of the border that was previously unfenced, and new pedestrian fencing over 14 percent of the border.

Most of Texas, which follows the Rio Grande and is largely privately owned land, is not fenced.

Here’s where I derive the numbers in the table above:

From report GAO-17-331, Southwest Border Security: Additional Actions Needed to Better Assess Fencing’s Contributions to Operations and Provide Guidance for Identifying Capability Gaps, published February 16, 2017:

From report GAO-23-105443, Southwest Border: Additional Actions Needed to Address Cultural and Natural Resource Impacts from Barrier Construction, published September 7, 2023: