Why is the border wall being painted black?

People walk alongside the border wall separating Mexico and the United States, near where it meets the Pacific Ocean Friday, July 25, 2025, in Tijuana, Mexico. Photo by: Gregory Bull / AP, file

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Homeland Security Secretary Kristi Noem announced that President Donald Trump has directed crews to paint the entire southern border wall black. Speaking to reporters near the border in New Mexico on Tuesday, Noem explained that painting has already begun on sections of the 30-foot steel barrier system, which extends from California to Texas along the U.S. border with Mexico.

According to Noem, Trump issued this directive with two objectives in mind: extending the steel structure’s durability by reducing rust and deterring border crossings by making the wall extremely hot to touch in the desert heat.

“We are going to be painting the entire border wall black,” Noem stated. When questioned about concerns that this approach could create more dangerous conditions for migrants, she replied, “Don’t touch it. People have a choice.”

Why would black paint make the wall hotter?

• Physics of color and heat absorption: Black paint absorbs nearly all wavelengths of visible sunlight. When the sun strikes a black surface, most of that energy turns into heat, causing the object’s temperature to rise more than a lighter-colored surface would. This is why black clothing or cars get hotter than lighter ones under the sun [1].
• Steel structure: The border wall consists of tall steel bollards, which naturally absorb solar heat. Painting them black would further increase this absorption, making them hotter to the touch during peak daylight hours — especially in the intense desert sun common along the border [2].

How hot would the wall get after being painted?

• Temperature estimates: While specific numbers for the border wall are lacking in official public documents, black-painted steel exposed to southern U.S. summer sun can become extremely hot — often reaching surface temperatures well above 130°F and, in some cases, up to 160°F or more for metal objects. However, experts note that black paint would increase the steel’s heat retention by less than 10% compared with unpainted surfaces, since the steel already absorbs a lot of heat in the sun [3].
• Real-world limits: As black paint weathers and fades under intense sunlight, it may lose some of its heat-absorbing effect, especially after several years [3].

Environmental concerns for painted wall

• Paint chemicals and maintenance: Painting hundreds of miles of border wall introduces significant quantities of paint chemicals into the environment. The paint will eventually need to be reapplied, as sun and weather break it down. Each round of repainting adds more chemical runoff risks, plus waste from old or peeling paint [3].
• Wildlife and habitat: The wall itself — as extensively reported by conservationists — has negative impacts on fragile desert ecosystems, blocking animal corridors, affecting water flows and disturbing protected areas. Adding paint may further disrupt these environments [4].
• Carbon footprint: The original steel construction already carries a massive carbon footprint. Additional industrial painting escalates the project’s overall environmental burden [5].

Humanitarian concerns for migrants

If the wall’s surface gets extremely hot, anyone attempting to climb it risks severe burns and heat stress. The combination of soaring temperatures, exposure, dehydration and injuries from falls makes these crossings even more dangerous. Medical facilities near the border have reported hundreds of migrants suffering trauma — especially after new wall sections were raised to 30 feet, and there’s a surge in injuries such as broken bones and burns from both falls and exposure to hot metal [6].

How many migrants have climbed the wall?

Recent hospital records (in southern California, for example) show hundreds of significant injuries every year directly related to border wall falls — over 440 in 2022 at one trauma center, with thousands of medical calls in nearby areas [9].

Cost and timeline for painting the wall

• Cost: Previous official estimates found that painting the entire wall black could cost at least $500 million for two coats of standard acrylic paint; more durable options — such as powder coating — could run into the billions. The lowest-cost option is about $1.2 million per mile of wall painted; higher-grade paint or coatings can cost $4-6.8 million per mile [10].
• Timeline and logistical challenges: Painting would require crews to revisit both new and already completed wall sections, increasing project time and complexities — especially when factoring in difficulties of reaching certain areas, working from the U.S. side only, and required equipment [3].
• Maintenance: Black paint in high-sun desert conditions will fade, potentially requiring repainting every decade, affecting long-term costs and logistics [3].

Criticism and controversy

Many view the black paint plan as excessive, unnecessary and expensive. Department of Homeland Security officials and military commanders have expressed skepticism, labeling it “costly and a significant long-term maintenance burden,” while technical experts note that the paint actually adds little additional heat beyond what unpainted steel would absorb [10].

Environmentalists, humanitarian workers and civil rights advocates warn the move could worsen harm to wildlife, raise suffering for migrants and further escalate an already contentious and expensive border project [11].