LaSalle is a city in LaSalle County, Illinois, United States, located at the intersection of Interstates 39 and 80. It is part of the Ottawa–Streator Micropolitan Statistical Area. Originally platted in 1837 over one square mile, the city's boundaries have grown to 12 square miles. 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 to the east. The population in 2010 is 9,601 down from 9,796 of the 2000 census. LaSalle and its twin city, Peru, make up the core of the Illinois Valley. Due to their combined dominance of the zinc processing industry in the early 1900s, they were collectively nicknamed "Zinc City."