The wall will cost a lot more — politically and economically — than Trump has publicly acknowledged. To build the wall along the nearly 2,000-mile border — and fulfill a key campaign promise — Trump will need to wield the power of government to forcibly take private properties, including those belonging to his supporters.

Much of the border, especially in Texas, snakes through farms, ranches, orchards, golf courses, and other private property dating back to centuries-old Spanish land grants. As a signpost to the troubles ahead, the government has still not finished the process from the last such undertaking a decade ago.

“It’s going to be time consuming and costly,” said Tony Martinez, an attorney who is mayor of the border town of Brownsville, Tex. “From a political perspective, you have a lot of rich landowners who were his supporters.”…

“It will be a huge challenge for his administration. It will clog up the courts,” said Terence Garrett, a security studies and public affairs professor at the University of Texas Rio Grande Valley in Brownsville. “It’s just an affront to property rights.”