Muscle Shoals is the largest city in Colbert County, Alabama, United States. It is located along the Tennessee River in the northern part of the state and, as of the 2010 census, the population of Muscle Shoals was 13,146. The estimated population in 2019 was 14,575. Both the city and the Florence-Muscle Shoals Metropolitan Area (including four cities in Colbert and Lauderdale counties) are commonly called "the Shoals". Northwest Alabama Regional Airport serves the Shoals region, located in the northwest section of the state.