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-Peru, IL Micropolitan Statistical Area. Originally platted in 1837 over one square mile, the city's boundaries have grown to 12 sq mi. 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.