In addition , the top 28 wealthiest places in Kentucky are in Jefferson County and seven of the 15 wealthiest counties in the state are located in the Louisville CSA.The second largest city is Lexington with a 2016 census population of 318,449 and its CSA , which includes the Frankfort and Richmond statistical areas , having a population of 732,372 .
Before 2017 , Lexington had a population of less than 320,000 .