The U.S.-Mexico border region is defined as 100 Km (62 miles) north and south of the international boundary. Two thousand miles long, the border region includes four states in the U.S. (California, Arizona, New Mexico and Texas) and six states in Mexico (Baja California Norte, Sonora, Chihuahua, Coahuila, Nuevo Leon and Tamaulipas).
Yeah, but the wall would be a billion feet high, covered with barbed wire and electric. And there would be 1,000 feet deep moat with crocodiles for every yard along with electric eels and pirahanas.
Of course, it would take a half a trillion dollars and about 20 years to build.