US Customs and Border Protection has awarded contracts to four general construction providers based in Alabama, Arizona, Mississippi, and Texas.

The Trump administration has awarded contracts to four companies to build concrete prototypes for a border wall between Mexico and the United States, marking a significant move towards fulfilling President Trump’s much-touted promise to curb immigration between the two countries.

The four companies, announced by US Customs and Border Protection (CBP) in a press conference yesterday, are Caddell Construction of Montgomery, Alabama; Fisher Sand & Gravel/DBA Fisher Industries of Tempe, Arizona; Texas Sterling Construction of Houston; and W.G. Yates & Sons Construction of Philadelphia, Mississippi. Designed to “deter illegal crossings,” the concrete prototypes must be between 18–30 feet high and span 30 feet; each will cost between $400,000 and $500,000. The CBP has reallocated the money from other programs, according to the New York Times.