Calvert City is a home rule-class city in Marshall County, Kentucky, United States. The population was 2,566 at the 2010 census.
Calvert City was named for Potilla Willis Calvert. He built his home, Oak Hill, in 1860 and around a decade later gave a portion of his land to a new railroad, specifying that a station be built near his home. That station served as the starting point of the town, which was incorporated on March 18, 1871. The railroad station and post office long favored the shorter Calvert, but the Board on Geographic Names reversed its earlier decision in 1957 and switched to the longer form.
By 1896, Calvert City was known as a sundown town, where African Americans were not allowed to reside. By 1908, the rest of Marshall County had also expelled its African American residents.
During the Ohio River flood of 1937, Calvert City's business district and much of the residential area was severely damaged by floodwaters.
In the 1940s, the construction of nearby Kentucky Dam by the Tennessee Valley Authority brought plentiful electric power that led to many industrial plants, mostly chemical manufacturers, to locate between the city and the Tennessee River. Merchant Luther Draffen was instrumental in attracting the dam and industrial plants.
According to the United States Census Bureau, the city has a total area of 13.9 square miles (36.1 km2), of which 13.9 square miles (35.9 km2) is land and 0.1 square mile (0.1 km2) (0.36%) is water.