Oklahoma City is 3 times larger than Huntsville, Alabama.
Area: 567 km2 calculated
Huntsville is a city located primarily in Madison County in the central part of the far northern region of the State of Alabama. Huntsville is the county seat of Madison County. The city extends west into neighboring Limestone County. Huntsville's population was 180,105 as of the 2010 census. Wikipedia
Area: 1,682 km2 calculated
Oklahoma City is the capital and largest city of the U.S. state of Oklahoma. The county seat of Oklahoma County, the city ranks 27th among United States cities in population. The population grew following the 2010 Census, with the population estimated to have increased to 610,613 as of July 2013. Wikipedia