LaSalle is a city in LaSalle County, Illinois, United States, located at the intersection of Interstates 39 and 80. It is part of the OttawaStreator Micropolitan Statistical Area. Originally platted in 1837 over one square mile, the city has grown to 12 square miles (31km2). City boundaries extend from the Illinois River and Illinois and Michigan Canal to a mile north of Interstate 80 and from the city of Peru on the west to the village of North Utica on the east. Starved Rock State Park is located approximately 5 miles (8.0km) to the east. The population was 9,796 at the 2000 census. LaSalle and its twin city, Peru, make up the core of the Illinois Valley.