Carter County, MT has a population of 1,561 according to the 2018 census. Located in east-central Montana between Miles City and Billings, it was established in 1921 from parts of Custer and Yellowstone counties. Carter County consists mostly of rolling hills covered with sagebrush and grasses that support cattle ranching as an important economic activity. Oil drilling also takes place here; there are both active and abandoned coal mines located within its borders as well.