The fence is a practical way to stop immigration and large parts of it have been built.  The Secure Fence Act of 2006 authorized the construction of at least two layers of reinforced fencing in high-crossing and high-risk sections along the border. This includes around the border town of Tecate, Calif., and a huge expanse stretching from Calexico, Calif., to Douglas, Ariz., which is virtually the entire length of Arizona's border with Mexico. Another section would stretch over most of the southern border of New Mexico. An additional section will wind through Texas, from Del Rio to Eagle Pass, and from Laredo to Brownsville. This would not only be a fence but will include technology to secure "operational control" of the border by using unmanned aerial vehicles, ground-based sensors, radar, satellites and cameras.1  1Weisman, Jonathan. "With Senate Vote, Congress Passes Border Fence Bill."