Billings is the largest city in the U.S. state of Montana, and the principal city of the Billings Metropolitan Area with a population of 169,676.  It is located in the south-central portion of the state and is the seat of Yellowstone County, which had a 2016 population of 158,980. The 2016 Census estimates put the Billings population at 111,150, making it the only city in Montana with over 100,000 people. The city is experiencing rapid growth and a strong economy; it has had and is continuing to have the largest growth of any city in Montana. Parts of the metro area are seeing hyper growth. With the Bakken oil development in eastern Montana and western North Dakota, the largest oil discovery in U.S. history, as well as the Heath shale oil discovery just north of Billings, the city's growth rate stayed high during the shale oil boom.  Although the city is still growing, the rate of increase has diminished markedly with oil price declines in recent years. Billings was nicknamed the "Magic City" because of its rapid growth from its founding as a railroad town in March 1882. The city is named for Frederick H. Billings, a former president of the Northern Pacific Railroad. Area attractions include Pompey's Pillar, Pictograph Cave, Chief Plenty Coups State Park, Zoo Montana, and Yellowstone Art Museum. Within 100 miles are Little Bighorn Battlefield National Monument, Bighorn Canyon National Recreation Area, Red Lodge Mountain Resort, and the Beartooth Highway, which links Red Lodge to Yellowstone National Park.