Plymouth is a city located in Marshall County Indiana. It is also the county seat of Marshall County. With a 2020 population of 9,946, it is the 80th largest city in Indiana and the 3120th largest city in the United States . Plymouth is currently declining at a rate of -0.18% annually and its population has decreased by -0.87% since the most recent census, which recorded a population of 10,033 in 2010. Plymouth reached it's highest population of 10,176 in 2014. Spanning over 8 miles, Plymouth has a population density of 1,313 people per square mile.
The average household income in Plymouth is $48,483 with a poverty rate of 24.67%. The median rental costs in recent years comes to $696 per month, and the median house value is $93,600. The median age in Plymouth is 35.7 years, 33.1 years for males, and 37.9 years for females.