Rockford is a city in Winnebago County, Illinois, United States. Located in far northern part of the state on the banks of the Rock River, Rockford is the county seat of Winnebago County (with a small portion of the city located in Ogle County). The most-populous Illinois city outside of the Chicago metropolitan area, the city is the fifth-largest city in Illinois and the 171st-most populous in the U.S.

Settled in the mid-1830s as Midway, Illinois (roughly equidistant between Lake Michigan and the Mississippi River), the location of the city became strategic for industrial development. During the second half of the 19th century, Rockford became notable for its production of heavy machinery, hardware, and tools. At the beginning of the 20th century, the city was the second leading center of furniture manufacturing in the United States. During the second half of the 20th century, Rockford struggled alongside many Rust Belt cities to maintain its previous industrial presence. Since the late 1990s, efforts in economic diversification have led to the growth of automotive, aerospace, and healthcare industries, as well as the undertaking of various tourism and downtown revitalization efforts.

Nicknamed the Forest City (denoting its heavily forested residential neighborhoods during much of the 20th century), Rockford is known for various venues of cultural or historical significance, including Anderson Japanese Gardens, Klehm Arboretum, Tinker Swiss Cottage, the BMO Harris Bank Center, the Coronado Theatre, the Laurent House, and the Burpee Museum of Natural History. Its contributions to music are noted in the Mendelssohn Club, the oldest music club in the United States, and performers such as Cheap Trick and Phantom Regiment Drum and Bugle Corps.