Streator is a city in LaSalle and Livingston counties in the U.S. state of Illinois. The city is situated on the Vermilion River approximately 81 …Streator is a city in LaSalle and Livingston counties in the U.S. state of Illinois. The city is situated on the Vermilion River approximately 81 miles southwest of Chicago in the prairie and farm land of north-central Illinois. As of the 2020 census, the population of Streator was 12,500.