Getting started with auto dealers license in Idaho, Nampa city. Nampa is the largest and fastest growing in Canyon County, Idaho, USA. The population of Nampa was 81 557 in 2010 census. Nampa is located about 20 miles (32 km) west of Boise along Interstate 84, and six miles (10 km) west of the meridian. Nampa is part of the metropolitan area of ??Boise. The name “Boise,” became a Shoshone word whose meaning is either a loafer or a footprint.