Johnston City is a city located in Williamson County Illinois. With a 2020 population of 3,307, it is the 402nd largest city in Illinois and the 5938th largest city in the United States . Johnston City is currently declining at a rate of -1.22% annually and its population has decreased by -6.66% since the most recent census, which recorded a population of 3,543 in 2010. Johnston City reached it's highest population of 7,137 in 1920. Spanning over 2 miles, Johnston City has a population density of 1,563 people per square mile.
The average household income in Johnston City is $54,193 with a poverty rate of 8.93%. The median rental costs in recent years comes to $532 per month, and the median house value is $65,800. The median age in Johnston City is 42.6 years, 35.5 years for males, and 44.8 years for females.