As the city grew, many factories and jobs came to Aurora, along with many people. In 1856, the Chicago, Burlington & Quincy Railroad located its railcar construction and repair shops in Aurora to become the town's largest employer until the 1960s. Many of the heavy industries were located on the East side which provided employment for four generations of European immigrants. Many immigrants flocked to the city, mainly from Great Britain, Ireland, Scandinavia, Luxembourg, Germany, France, and Italy.The professional and managerial workers more likely came from Yankee stock and settled across the river, making the West side more affluent. Aurora became main economic center of the Fox Valley area. The combination of these three factors—a highly industrialized town, a sizable river that divided it, and the Burlington's shops—account for much of the dynamics of Aurora's political, economic, and social history. Both sides of Aurora still maintain a rivalry which is enacted through yearly high school football/basketball games. This is the oldest high school rivalry in the state of Illinois.[4]

Beginning in the boom period, the town was inclusive and tolerant, and welcomed a variety of immigrants and openly supporting abolitionism prior to the American Civil War. Mexican migrants began arriving after 1910. Socially, the town was progressive in its attitude toward education, religion, welfare, and women. The first free public school district in Illinois was established in 1851 and a high school for girls four years later. By 1887, 20 congregations (including two African American churches) representing nine denominations were established, and a YWCA started in 1893, still in operation today.[2]

The city was a manufacturing powerhouse until 1974, when the railroad shops began to close. Soon many other factories and industrial areas relocated or went out of business. By 1980, there were few operating industrial areas in the city, and unemployment soared to 16%.[2] Although development of the Far East side at Fox Valley Mall brought stimulus, it helped lead to the decline of the downtown area on Stolp Island. Starting in the late 1980s, several business and industrial parks were established on the outskirts of the city. Today some of the old industrial districts have been reoccupied as warehouses. In 1993, a casino was built downtown, which brought redevelopment to the downtown area. In the late 1990s, more development began in the rural areas outside of Aurora. Subdivisions sprouted up all around the city; Aurora's population soared. Today, approximately 70,000 of the city's residents live in these areas of the city.