The black paint will also prevent rust on the steel, said US Border Patrol Chief Michael Banks.

Homeland Security Secretary Kristi Noem said the entire southern border wall will be painted black, so it will get hot in the sun and "make it even harder for people to climb."

Noem said the change would help encourage migrants not to come into the U.S. without authorization, “but that they will abide and come to our country the right way, so that they can stay and have the...