Marengo is a city located in McHenry County Illinois. With a 2020 population of 7,375, it is the 272nd largest city in Illinois and the 3834th largest city in the United States . Marengo is currently declining at a rate of -0.42% annually and its population has decreased by -3.57% since the most recent census, which recorded a population of 7,648 in 2010. Marengo reached it's highest population of 7,673 in 2010. Spanning over 8 miles, Marengo has a population density of 935 people per square mile.
The average household income in Marengo is $80,315 with a poverty rate of 13.37%. The median rental costs in recent years comes to $912 per month, and the median house value is $154,200. The median age in Marengo is 36.7 years, 36.4 years for males, and 36.9 years for females.