Jacksonville, Florida is 6 times larger than Knoxville, Tennessee.
Area: 1,988 km2 calculated
Jacksonville is the largest city in the U.S. state of Florida by population and the largest city by area in the contiguous United States. It is the county seat of Duval County, with which the city government consolidated in 1968. Wikipedia
Area: 332 km2 calculated
Knoxville is a city in the U.S. state of Tennessee, and the county seat of Knox County. The city had a population of 178,874 as of the 2010 census and an estimated population of 183,270 in 2013, making it the state's third largest city. Wikipedia