Ottawa is a city located in Illinois. With a 2020 population of 17,951, it is the 140th largest city in Illinois and the 2026th largest city in the United States . Ottawa is currently declining at a rate of -0.31% annually and its population has decreased by -4.35% since the most recent census, which recorded a population of 18,768 in 2010. Ottawa reached it's highest population of 19,408 in 1960. Spanning over 14 miles, Ottawa has a population density of 1,403 people per square mile.
The average household income in Ottawa is $65,160 with a poverty rate of 17.11%. The median rental costs in recent years comes to $819 per month, and the median house value is $128,000. The median age in Ottawa is 38.7 years, 35.3 years for males, and 41.7 years for females.