Rankin County is a county located in the U.S. state of Mississippi. The western border of the county is formed by the Pearl River. As of the 2020 census, the population was 157,031, making it the fourth-most populous county in Mississippi. The county seat is Brandon. The county is named in honor of Christopher Rankin, a Mississippi Congressman who served from 1819 to 1826.

The Pearl River is a river in the U.S. states of Mississippi and Louisiana. It forms in Neshoba County, Mississippi from the confluence of Nanih Waiya and Tallahaga creeks, and has a meander length of 444 miles (715 km). The lower part of the river forms part of the boundary between Mississippi and Louisiana.