The city of LaSalle is located in LaSalle County, Illinois, at the intersection of Interstate 80 and Interstate 39. It is part of the Ottawa–Streator Micropolitan Statistical Area. Originally platted in 1837 over one square mile, the city has 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.
Before settlers came to the area, the Illinois Valley was inhabited by a people known as the Mound Builders and the Native Americans. Because of the limited amount of written records concerning these people, very little is known about their lives and activities.
The first recorded journey through the area is that of Louis Joliet and Father Marquette in the late 1660’s. They passed through the area on their way west, and Father Marquette later returned to found a mission near what is now Starved Rock.
Rene-Robert Cavelier Sieur de LaSalle, for whom the city is named, began is exploration of the area in 1678. After traveling the Mississippi River, he and Henri di Tonty built Fort Saint Louis at Starved Rock. He continued to travel, building forts, until his murder in January 1687.
After Illinois declared statehood on December 3, 1818, it was only a matter of time before settlers began moving into the Illinois Valley. LaSalle County was established on January 15, 1831.