The numbers are out from the U.S. Census Bureau and three Kentucky counties rank among the nation's fastest growing.
Spencer County grew by 40 percent between 2000 and 2006, ranking the 18th fastest-growing county in the nation.
In northern Kentucky, Boone County ranked number 71 on the list, with a 28 percent population surge in six years.
Scott County came in as the 88th fastest growing. It grew by 26-percent.
Jessamine and Madison Counties also had double digit growth. Fayette County's growth was slightly less than the state's overall growth at less than 4 percent.