The Billings Metropolitan Statistical Area is the largest and fastest growing metropolitan area in the U.S. state of Montana. Located in the south central portion of the state, its population was 166,855 at the 2014 United States Census estimate.It is located in Carbon and Yellowstone counties, and has one of the largest trade, cultural, business and medical areas in the United States; this includes all of Montana, northern Wyoming and the western Dakotas.