A family looks toward metal bars marking the United States border where it meets the Pacific Ocean in Tijuana, Mexico. (Gregory Bull/AP)

When the Texas Tribune contacted members of that state’s congressional delegation last year to solicit opinions on then-Republican presidential nominee Donald Trump’s proposed wall on the border with Mexico, the responses were not overwhelmingly positive. Democrats were pretty united in opposition, but even Republicans frequently expressed concerns. Did it need to cover every square inch of the border? Does it need to be a wall? How to deal with geographically difficult areas?

On the surface, this is surprising: Even members of Trump’s own party in one of the states that directly adjoins Mexico offered some hesitation. But in another sense, it’s not that surprising. If built the length of the border, the wall would be traversing mostly Democratic-blue territory.

We should note up front that barriers — including walls — already exist along the border with Mexico. The University of Texas Law School maintains a collection of maps, proposed and actual, of border fencing. Take this snippet of a 2013 map, showing the point at which Arizona, Mexico and California merge.


In this one area, there are three types of fence: pedestrian fence 225 (PF225), vehicle fence 300 (VF300) and legacy pedestrian fencing, illustrated in magenta. Viewed from the Mexican side, looking in the direction of the arrow, this is what that intersection looks like.

In a relatively flat, populated area, constructing a barrier is fairly easy. Along other parts of the border, it isn’t.

That’s one of the practicality issues. (Another? Finding an affordable — and legal workforce.) But we’re more interested in the political issues.

With the help of Mapzen (and maps guru burritojustice), we created this interactive map of the Mexican border.


(Congressional vote data from DailyKos. Wall data by Michael Corey, Reveal News.)

When you’re zoomed out, you can see each of the nine congressional districts that line the border. Voters in eight of those nine districts voted for Democratic nominee Hillary Clinton over Trump; in five districts, her margin of victory was over 15 points. Clinton overperformed: In three of the nine districts, Republicans won election to the House. (That aligns with the Cook Political Partisan Voting Index.)

District Representative Presidential result House result Cook index
CA-51 Rep. Juan Vargas (D) Clinton +49 D +45.6 D +16
AZ-2 Rep. Martha McSally (R) Clinton +4.9 R +14 R +3
AZ-3 Rep. Raúl M. Grijalva (D) Clinton +29.9 D +88.1 D +8
NM-2 Rep. Steve Pearce (R) Trump +10.2 R +25.5 R +5
TX-15 Rep. Vicente Gonzalez (D) Clinton +16.7 D +19.6 D +5
TX-16 Rep. Beto O’Rourke (D) Clinton +40.7 D +85.7 D +12
TX-23 Rep. Will Hurd (R) Clinton +3 R +1.3 R +3
TX-28 Rep. Henry Cuellar (D) Clinton +19.8 D +34.9 D +7
TX-34 Rep. Filemon Vela (D) Clinton +21.5 D +25.4 D +8

There are 33 Hispanic members of the House. Five of them represent districts on the border with Mexico.

Will Hurd is not Hispanic, but is the Republican who holds the most tightly contested district of those adjacent to the border. He released a statement about the wall this week that echoes what he told the Texas Tribune last year.

“Building a wall is the most expensive and least effective way to secure the border,” Hurd’s statement read. “Each section of the border faces unique geographical, cultural, and technological challenges that would be best addressed with a flexible, sector-by-sector approach that empowers the agents on the ground with the resources they need. A wall may be an effective tool in densely populated areas, but a variety of tools are needed between Brownsville, Texas and San Diego, California.”

At the county level — zoom in — the political picture changes somewhat. Individual counties were more of a mixed bag in terms of the candidate residents supported in the presidential election. Of the 23 counties abutting the border, nine backed Trump. Many of those counties, though, have relatively small populations. Across the 23 counties, Trump earned 786,000 votes to Clinton’s 1.3 million. (Clinton earned 58.6 percent of the vote in those counties.) A little over 100,000 people live in counties Trump won. Counties Clinton won? 2.1 million.

Field of Vision – Best of Luck with the Wall from Field Of Vision on Vimeo.

Back to the wall. Zoom in on Pima County, Arizona. The gaps in the wall there? Mostly a function of the terrain.

Move to the east, near where Texas meets the Gulf of Mexico and notice where the existing parts of the wall are located: Well into American territory. This is another geographic problem that leads to a political problem. Because of protections against building in the flood plain of the Rio Grande, the wall is built more inland, stranding farms and golf courses on the other side of the wall. Eagle Pass, the town where the golf course is located, sued to block the construction of the wall — unsuccessfully.

In other words, President Trump’s proposed wall will be built mostly in places that voted against him and to some extent in places that don’t want it. And at this point, there’s no reason to think that anyone besides American citizens will end up paying for it.