Fort Smith is the third-most populous city in Arkansas, United States, and one of the two county seats of Sebastian County. As of the 2020 census, the population was 89,142. It is the principal city of the Fort Smith, Arkansas–Oklahoma Metropolitan Statistical Area, a region of 298,592 residents that encompasses the Arkansas counties of Crawford, Franklin, and Sebastian, and the Oklahoma counties of LeFlore and Sequoyah.

Sebastian County is a county located in the U.S. state of Arkansas. As of the 2020 census, the population was 127,799, making it the fourth-most populous county in Arkansas. The county has two county seats, Greenwood and Fort Smith.