Monongahela is a city located in Washington County Pennsylvania. With a 2020 population of 4,056, it is the 242nd largest city in Pennsylvania and the 5365th largest city in the United States . Monongahela is currently declining at a rate of -0.56% annually and its population has decreased by -5.67% since the most recent census, which recorded a population of 4,300 in 2010. Monongahela reached it's highest population of in . Spanning over 2 miles, Monongahela has a population density of 2,120 people per square mile.
The average household income in Monongahela is $62,791 with a poverty rate of 9.35%. The median rental costs in recent years comes to $676 per month, and the median house value is $81,800. The median age in Monongahela is 40.7 years, 38.3 years for males, and 41.8 years for females.