Hardin is a home rule-class city in Marshall County, Kentucky, United States. The population was 580 at the 2020 census. The Paducah, T…Hardin is a home rule-class city in Marshall County, Kentucky, United States. The population was 580 at the 2020 census. The Paducah, Tennessee and Alabama Railroad reached the area in 1890. A community grew up around the depot, erected on land purchased from local landowner Hardin D. Irvan. The post office was established on October 31, 1891, but the town was formally incorporated as a city on March 25, 1952.