President Donald Trump made a promise during his speech at the Conservative Political Action Conference on Friday.
"We're going to build a wall," Trump said. "Don't worry about it. We're building the wall; we're building the wall. In fact, it's going to start soon, way ahead of schedule."
And not long after, U.S. Customs and Border Protection released a notification that it will soon take submissions for "prototype wall structures."
It's the first tangible step toward meeting Trump's executive order on border security that he signed in January. Trump has said the barrier would run for 1,000 miles along the nearly 2,000-mile border with Mexico. Some sort of barrier already runs some 700 miles along the border.
Trump routinely calls his proposed border structure a "wall." But he has said before that some areas might be fenced instead.
He estimates it will cost $12 billion, but some have said a wall that's 1,000 miles long, 50 feet tall and 10 feet below ground could cost upwards of $38 billion to build.
The American people and American companies will foot the bill. Trump has said Mexico will pay the U.S. back, but Mexico's current president and two former presidents have said that's not going to happen.