Throughout the 19th century, Congress promoted exploration of the American West. As the United States grew “from sea to shining sea” with the Louisiana Purchase and the Mexican Cession from the Treaty of Guadalupe Hidalgo, white settlers changed the landscape as they transformed forests into fields. However, some of the people already living in the West did not want to be part of the American empire. Trace the challenges and questions Congress and the American people have faced as they turned to the West.