In the 1850s government-sponsored surveys to chart the remaining unexplored regions of the West, and to plan possible routes for a transcontinental railroad. Much of this work was undertaken by the Corps of Engineers, Corps of Topographical Engineers, and Bureau of Explorations and Surveys, and became known as "The Great Reconnaissance". Regionalism animated debates in Congress regarding the choice of a northern, central, or southern route. Engineering requirements for the rail route were an adequate supply of water and wood, and as nearly-level route as possible, given the weak locomotives of the era.