U.S. Census Office, Location of Areas Irrigated in 1889 (1898)

Irrigation was a critical necessity for westward expansion, and the end of the 19th century was an important period of transition in irrigation, as small-scale, local efforts shifted to large-scale, state-supported projects. This map, featured in the 1898 Statistical Atlas of the United States based upon the Results of the Eleventh Census, which was published by the U.S. Census Office under the direction of Henry Gannett, shows the irrigated areas in the Western United States as of 1889. Still in its infancy, the Western irrigation system consisted of water diverted from rivers and streams peppered throughout the region. Shortly after this map was published, in 1902, President Theodore Roosevelt signed the National Reclamation Act of 1902, authorizing federal funding for irrigation projects in 16 (later 17) arid Western states. Spearheaded by Representative Francis G. Newlands, it created the U.S. Reclamation Service (now Bureau of Reclamation) with the purpose of building dams and canals, funded by public land sales to encourage Western settlement.