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 2017 census population of 321,959 and its CSA , which includes the Frankfort and Richmond statistical areas , having a population of 740,364 .
After 2016 , Lexington had a population of more than 320,000 .