Five Georgia companies are among more than 200 nationwide that have signaled interest in helping build President Donald Trump's signature campaign promise: A "great, great wall" on the U.S.-Mexico border.

Located in the Atlanta and Augusta areas, the Georgia businesses include construction companies, an engineering firm, a building industry recruiter and a defense contractor. All have added their names to an online federal list of vendors interested in competing to design a prototype for a concrete border wall. Proposals were due yesterday.

Trump says the wall will help curb illegal immigration and boost national security.

Estimates for extending the existing barriers along the southwest border — there are already about 700 miles of various walls, fences and other barriers there — range as high as $21.6 billion. Critics call the proposal a divisive and colossal waste of money, noting that a large share of those who are here without authorization did not sneak across the 2,000-mile border but instead came here legally and then overstayed their visas.

Read more about the Georgia businesses that signaled they're interested in helping build a mock-up for the wall here.