Rock Island is a city in Rock Island County, Illinois, United States. The population was 39,684 at the 2000 census. It is the county seat of Rock Island County^GR6 and is one of the Quad Cities, along with neighboring Moline and the Iowa cities of Davenport and Bettendorf.

Part of Road to Perdition (2002) takes place in Rock Island.

The Chicago, Rock Island & Pacific Railroad was founded here in 1851 and was known as the Rock Island Line. The railroad was liquidated in bankruptcy in 1980.

Rock Island is also home to the Rock Island Arsenal on Arsenal Island. It is an active factory producing ordinance and weapons components for the U.S. Army. The Arsenal provides six thousand civilian jobs for the local area.

The first railroad bridge across the Mississippi River was built between Arsenal Island and Davenport in 1856. Steamboat pilots of the day, fearful of competition from the railroads, considered the new bridge "a hazard to navigation". Two weeks after the bridge opened, the steamboat Effie Afton rammed part of the bridge and started it on fire. Legal proceedings ensued - with a young lawyer named Abraham Lincoln defending the railroad. The lawsuit went all the way up to the Supreme Court, and was eventually ruled in favor of Lincoln and the railroad. Although the original bridge is long gone, a monument exists on Arsenal Island marking the Illinois side. Bridge Street, in Davenport, is the location of the Iowa side.

The south shore of Rock Island, on the Rock River, occupies the site of the former village of Saukenuk, where Chief Blackhawk was born. The Black Hawk State Historic Site includes much, but not all, of the site of the original village of Saukenuk. The park includes a museum and a number of pleasant hiking trails along the Rock River and surrounding woods.