The Boise City–Nampa, Idaho Metropolitan Statistical Area (MSA) or Boise City-Mountain Home-Ontario, ID-OR Combined Statistical Area (commonly known as the Boise Metropolitan Area or the Treasure Valley), as defined by the United States Census Bureau, is an area consisting of seven counties in southwestern Idaho, and Malheur County, Oregon  anchored by the cities of Boise and Nampa. It is the state's largest officially designated metropolitan area and includes Idaho's three largest cities – Boise, Nampa, and Meridian. Nearly 40 percent of Idaho's total population lives in the area.