Nampa is the most populous city in Canyon County, Idaho, United States. The population was 100,200 at the 2020 census. It is Idaho's 3rd most populous city. Nampa is about 20 miles (32 km) west of Boise along Interstate 84, and 6 miles (9.7 km) west of Meridian. It is the second principal city of the Boise metropolitan area. The name "Nampa" may have come from a Shoshoni word meaning either 'moccasin' or 'footprint'. According to toponymist William O. Bright the name comes from the Shoshoni word /nampai/, meaning "foot".

Canyon County is located in the U.S. state of Idaho. As of the 2020 Census, the population was 231,105, which by 2022 was estimated to have risen to 251,065. making it the second-most populous county in Idaho. The county seat is Caldwell, and its largest city is Nampa. Canyon County is part of the Boise metropolitan area.