McNairy County is a county located in the U.S. state of Tennessee. As of the 2020 census, the population was 25,866. The county seat and largest city is Selmer. McNairy County is located along Tennessee's border with the state of Mississippi. Sheriff Buford Pusser, whose story was told in the Walking Tall series of movies, was the sheriff of McNairy County from 1964 to 1970.