Millington is a city in Shelby County, Tennessee, United States. As of the 2010 census, it had a population of 10,176. Millington was granted the title "Flag City Tennessee" by the Tennessee State Legislature. The Naval Support Activity Mid-South is located at the former Memphis Naval Air Station, which was changed functions from a training base to an administrative one in 1993. There is also a general aviation airport that features the third longest runway in Tennessee.