Rockford is its third-largest city
The city's current population is also compared to its peak population, ... Rockford 
is the third-largest city in Illinois, but it could eventually fall to... [DOC] [TLE] Illinois population shifts | NIU Newsroom [PAR] May 26, 2015 ... Rockford sees substantial decline; Naperville, Elgin, Aurora add residents ... 
indicate that Rockford, the third largest city in Illinois, is leading the state ...