Trump admin says border wall to be painted black to deter migrants. Will it work?

Since returning to office, President Donald Trump has intensified his crackdown on illegal immigration — escalating deportations, declaring a border emergency and directing billions toward enforcement.

Now, his latest tactic is unexpectedly simple: a fresh coat of paint.

Department of Homeland Security Secretary Kristi Noem announced Aug. 19 that the “entire” U.S.-Mexico border wall will be painted black to deter migrants.

“That is specifically at the request of the president, who understands that in the hot temperatures down here when something is painted black it gets even warmer and it will make it even harder for people to climb,” she said.

Noem — who painted a section of the wall herself — wrote on X that the new coating will be “so hot to the touch that criminal illegal aliens won’t even try.”

This idea has been around for a while. In 2020, during the first Trump administration, officials tested black paint on some sections of the border wall.

But experts — for a number of reasons — are skeptical that a paint job will have much of an impact on rates of illegal immigration.

Black paint won’t be much hotter

For one, black paint won’t drastically increase the temperature of the wall, much of which is made of steel, Richard Duncan, a mechanical engineer and building scientist, told McClatchy News.

“The primary source of heat gain for this wall is infrared solar radiation,” Duncan said. “In general, darker surfaces absorb more heat due to higher emissivity—the measure of a material’s ability to absorb and emit infrared energy.”

But, darker shades do not inherently equate to more heat since there are other factors at play.

If the steel wall is left unpainted, it will oxidize or rust, a process that increases its emissivity, Duncan said. In contrast, black paint will deteriorate under prolonged sun exposure, becoming gray and decreasing its emissivity.

“Therefore, the net thermal impact of painting the wall black versus allowing it to rust is minimal,” Duncan said.

He also added that, in arid climates like the U.S.-Mexico border region, minimal moisture leads to low corrosion rates.

“Given these factors, applying a protective coating may not be economically or functionally justified,” he concluded.

Many don’t climb the wall

Another factor to consider is that many migrants coming into the U.S. from Mexico do not climb over the border wall, experts said.

“The number of individuals that are crossing over the fence is very small,” Tony Payan, the director of the Center for the U.S. and Mexico at Rice University’s Baker Institute for Public Policy, told McClatchy News.

“Most of the border is unwalled and migrants just go around the fortified zones or enter surreptitiously through ports of entry,” Douglas Massey, emeritus professor of sociology at Princeton University, who researches global immigration, told McClatchy News.

The U.S.-Mexico border stretches roughly 1,954 miles, yet only around 500 miles feature physical barriers, primarily along the California, Arizona, and New Mexico sections, according to a 2020 BBC analysis. An additional 50 miles has been constructed in Texas since 2021, and plans are underway to extend the barrier further in other states, officials say.

And while some sections of the barrier are made of tall steel bollards — measuring up to 30 feet high — others are composed of mesh or chain-link fencing, according to the U.S. Customs and Border Protection.

“Many migrants seeking to enter the United States from Mexico without permission enter between sections of border fencing,” Julia Gelatt, associate director of the U.S. Immigration Policy Program at the Migration Policy Institute, told McClatchy News. “And under President Biden, many waited in line at ports of entry to seek permission to enter through the CBP One process.”

Still, she said, some migrants do attempt to cross into the U.S. where there is a border wall.

“With the help of smugglers, migrants may enter through tunnels under the fence, through holes cut through the fence, or climb over the fence,” Gelatt said.

Of those who opt to climb, would they be dissuaded by a new coat of paint?

“I suspect that black paint would not be a big factor in deterring migrants who are set on crossing the border into the United States,” Gelatt said.

A USA Today analysis found that, in 2022, nine people died falling from the border fence and several hundred more were injured.

Border crossings at historic lows

The paint job may also have little impact due to the success of Trump’s other policies. Since he took office, border crossings have dropped dramatically.

In June, just over 6,000 people were apprehended while trying to illegally cross into the U.S. at the southern border, the lowest such figure ever recorded, according to CBS News. By comparison, during many months in Biden’s term, apprehensions surpassed more than 6,000 per day — and sometimes topping 10,000.

“The number of individuals showing up at the border is already low,” Payan said. So painting the entire border wall “seems like a waste of resources to deter probably a few hundred individuals.”

When contacted by McClatchy News, a DHS spokesperson declined to provide a price estimate for the paint project, though they noted the recently passed “One, Big Beautiful Bill” allocates significant funding for the wall.

“With the OBBB we will be able to finish the border wall system started under President Trump’s first term,” the spokesperson said. “Due to an active procurement process to finish the wall it would be irresponsible to the American taxpayer to release the numbers as it may impact future bids.”

A Washington Post analysis from 2020 estimated painting the border wall black would cost about $500 million.

This story was originally published August 22, 2025 at 1:39 PM with the headline "Trump admin says border wall to be painted black to deter migrants. Will it work?."