Coal county is located in southeastern Oklahoma and Coalgate is the county seat. As the name suggests, the county was heavily involved in the coal industry in the mid-19th century. It ranked second only to Pittsburg county in total production. Coal mining camps sprang up and became the basis of growth into viable towns. Some, however, became ghost towns including Cairo about seven miles northeast of Coalgate and Cottonwood about two miles northeast of Coalgate. Today several mines have closed and production has slipped from previous levels.

Other than a small arm of Atoka Lake and the headwaters of Muddy Boggy Creek, no major bodies of water can be found in the county.

The county population on July 1, 1999, was 6,126, an increase of 346 over the 1990 census.