The U.S. Army Corps of Topographical Engineers was established by the United States Congress in 1838. It was made up of only officers who were hand-picked graduates of the United States Military Academy at West Point. Their main purpose was to map and make military surveys for routes to the Pacific. They were at the center of the westward expansion of the United States between the War of 1812 and the American Civil War. They mapped the frontier regions of the West encouraging Americans to move into those areas. They laid out trails, roads, railroad routes and waterways. During the Civil War, the functions of the Corps of Topographical Engineers were transferred to the Army Corps of Engineers.