The Ottawa, IL Micropolitan Statistical Area, as defined by the United States Census Bureau, is an area consisting of three counties in north central Illinois, anchored by the city of Ottawa. Peru and Streator are former primary cities.

LaSalle or La Salle is a city in LaSalle County, Illinois, United States, located at the intersection of Interstates 39 and 80. It is part of the Ottawa, IL Micropolitan Statistical Area. Originally platted in 1837 over one square mile, the city's boundaries have grown to 12 sq mi (31 km2). 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 mi (8 km) to the east. The population was 9,582 as of the 2020 census, down from 9,609 at the 2010 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."