Hardin is a city in Marshall County, Kentucky, United States. The population was 564 at the 2000 census. As of the census of 2000, there were 564 people, 257 households, and 155 families residing in the city. The population density was 954.8 people per square mile (369.1/square/km). There were 282 housing units at an average density of 477.4 per square mile (184.5/square/km). The racial makeup of the city was 99.29% White, 0.53% Native American, and 0.18% from two or more races. Hispanic or Latino of any race were 0.35% of the population.