Arlington Heights is a village in Cook County in the U.S. state of Illinois. A suburb of Chicago, it lies about 25 miles northwest of the city's downtown. The population was 75,101 at the 2010 census. It is the most populous community in the United States that is incorporated as a "village", although it is not far ahead of its nearby Illinois neighboring villages of Schaumburg and Bolingbrook and adjacent Palatine.Arlington Heights is known for Arlington Park Race Track, home of the Arlington Million, a Breeders' Cup qualifying event; it also hosted the Breeders' Cup Classic in 2002. The village is also home to the Arlington Heights Memorial Library, which has one of the largest collections in the state.