Aurora is a city in the Chicago metropolitan area located partially in DuPage, Kane, Kendall, and Will counties in the U.S. state of Illinois. Located primarily in DuPage and Kane counties, it is the second most populous city in Illinois, after Chicago, and the 144th most populous city in the United States. The population was 197,899 at the 2010 census, and was 180,542 as of the 2020 Census.Founded within Kane County, Aurora's city limits have expanded into DuPage, Will, and Kendall counties. Once a mid-sized manufacturing city, Aurora has grown since the 1960s. From 2000 to 2009, the U.S. Census Bureau ranked the city as the 46th fastest growing city with a population of over 100,000.In 1908, Aurora adopted the nickname "City of Lights", because in 1881 it was one of the first cities in the United States to implement an all-electric street lighting system. Aurora's historic downtown is located on the Fox River, and centered on Stolp Island. The city is divided into three regions, the West Side, on the west side of the Fox River, the East Side, between the eastern bank of the Fox River and the Kane/DuPage County line, and the Far East Side/Fox Valley, which is from the County Line to the city's eastern border with Naperville.
The Aurora area has some significant architecture, including structures by Frank Lloyd Wright, Ludwig Mies van der Rohe, Bruce Goff and George Grant Elmslie. Aurora is also home to over 50 Sears Catalog Homes and seven Lustron all-steel homes. The Hollywood Casino Aurora, a dockside gaming facility with 53,000 square feet (4,900 m2) and 1,200 gaming positions, is located along the river in downtown Aurora.