Old Mill Creek is a city located in Illinois. With a 2020 population of 163, it is the 1172nd largest city in Illinois and the 17236th largest city in the United States . Old Mill Creek is currently declining at a rate of -1.21% annually and its population has decreased by -8.43% since the most recent census, which recorded a population of 178 in 2010. Old Mill Creek reached it's highest population of in . Spanning over 11 miles, Old Mill Creek has a population density of 15 people per square mile.
The average household income in Old Mill Creek is $90,173 with a poverty rate of 1.03%. The median rental costs in recent years comes to $1,214 per month, and the median house value is $541,700. The median age in Old Mill Creek is 61.3 years, 61 years for males, and 65.8 years for females.