From 1942 to 1945, secret government trains regularly delivered civilians from the United States and Latin America to Crystal City, a small desert town at the southern tip of Texas. The trains carried Japanese, German, and Italian immigrants and their American-born children to a family internment camp, the only one during World War II. Crystal City was the center of a government exchange program. During the war, hundreds of prisoners, including their children, were exchanged for ostensibly more important Americans---diplomats, businessmen, soldiers, physicians, and missionaries that were behind enemy lines in Japan and Germany.