Much of what Customs and Border Protection has been working on along the border is replacement barrier.

According to CBP, the agency used fiscal year 2017 funds to construct "approximately 38 of 40 miles of wall in place of outdated designs in San Diego and El Centro, California, Santa Teresa, New Mexico and El Paso, Texas."

A CBP official said "this barrier replaced dilapidated infrastructure, half of which was Normandy-style vehicle barrier." Vehicle barriers are low to the ground. It would stop a car, but people can easily step over it.

CBP also said construction has "started on the San Diego Secondary replacement, the first project funded in FY 2018," adding that "the first new wall project, where no barrier currently exists, is anticipated to start in April in Hidalgo County of the Rio Grande Valley Sector."

The spending bill passed in February included $1.375 billion for approximately 55 miles of new barriers in the Rio Grande Valley sector.