Original sentence: As of the 2000 census, the city population was 142,990, making it the third-largest city in Illinois; in 2003, a special census found the city's population to be 157,267.Some Aurora residents claim this makes it the second-largest city in Illinois, behind Chicago and just ahead of Rockford, but Rockford was not recounted at the same time, thus the matter may not be settled until the 2010 US Census
Edited sentence: (Some Rockford residents dispute the claim, as their city was not recounted at the same time, thus the matter may not be settled until the 2010 US Census).As of the 2000 census, the city population was 142,990, making it the third-largest city in Illinois; in 2003, a special census found the city's population to be 157,267, making it the second-largest city in Illinois, behind Chicago and just ahead of Rockford