The Great Wall of China was started during the Qin Dynasty (221-206 B.C.) and enlarged to 4,000 miles during the Ming Dynasty (1368-1644 A.D.). The largest construction project ever completed, it is a feature visible from Earth orbit. Made with human labor from masonry, rocks, and packed earth, the wall has a thickness of from 15 to 30 feet and a height up to 25 feet.
Many walls have been built throughout man’s history to hinder foreign invaders, including the walled cities described in the Bible. An exception was the Berlin Wall, used to keep East Germans from leaving. A recent controversial wall and fence being built by Israel has been largely successful in deterring suicide bombers.
The 2,100 mile border between the United States and Mexico traverses a variety of terrains, including urban areas and deserts. Barriers have been built in metropolitan centers, location of the greatest number of illegal crossings. U.S. Congressman Duncan Hunter has proposed the construction of a reinforced fence along the entire United States – Mexican border.
In 1962, Vice President Lyndon Johnson received the following message from a Native American Chief on a reservation. “Be careful with your immigration laws. We were careless with ours.”