Knoxville, Tennessee is 7.1 times larger than Allentown, Pennsylvania.
Area: 47 km2 calculated
Allentown is a city located in Lehigh County, Pennsylvania, United States. It is Pennsylvania's third most populous city, after Philadelphia and Pittsburgh, and the 224th largest city in the United States. 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