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.