Caldwell (population 25,967), the county seat of Canyon County, was named for Senator C.A. Caldwell, president of the Idaho and Oregon Land Improvement Company, which platted the townsite along the railroad.
First a tent city, the community grew quickly to become the hub of agriculture and transportation for Southwest Idaho and the desert Northwest. Caldwell is located in Treasure Valley, and the construction of Federal irrigation reservoirs in 1906 and 1915 transformed the arid area into cultivated fields, sparking further growth in Caldwell. In addition to being a commercial hub, the community became a cultural center with the founding of the College of Idaho (now known as Albertson College) in 1891.
Caldwell has three historic districts listed in the National Register of Historic Places. A locally designated district, the Steunenberg Residential Historic District, is one of the most historically intact neighborhoods in Idaho, possessing more than 330 residential properties.
The city's Historic Preservation Commission oversees preservation activities in the community and is working with the Friends of the Depot and other groups to preserve the Caldwell Oregon Short Line Depot (1906). Located at the heart of the historic downtown, the building is being renovated for use as an interpretive/tourist center and community meeting space. A plaza is being developed at the depot to host a regular farmer's market and other outdoor events in the historic district.
Designated a Preserve America Community in April 2005.