Plymouth is a city in Marshall County, Indiana, United States. The population is 10,214 in the 2020 census. It is the county seat of Marshall County. Plymouth was the site of the first retail outlet of defunct U.S. retailer Montgomery Ward in 1926. Geography Plymouth, Indiana is located at (41.343894, -86.312544), along the Yellow River. According to the 2010 census, Plymouth has a total area of , of which (or 99.47%) is land and 0.04 square mile (0.1 km2) (or 0.53%) is water. Demographics 2010 census As of the census of 2010, there were 10,033 people, 3,940 households, and 2,401 families residing in the city. The population density was . There were 4,451 housing units at an average density of . The racial makeup of the city was 87.2% White, 0.9% African American, 0.6% Native American, 0.5% Asian, 8.3% from other races, and 2.5% from two or more races. Hispanic or Latino of any race were 20.0% of the population. There were 3,940 households, of which 34.6% had children under the age of 18 living with them, 39.7% were married couples living together, 14.9% had a female householder with no husband present, 6.3% had a male householder with no wife present, and 39.1% were non-families. 33.5% of all households were made up of individuals, and 15% had someone living alone who was 65 years of age or older. The average household size was 2.49 and the average family size was 3.19. The median age in the city was 34.3 years. 27.9% of residents were under the age of 18; 9.3% were between the ages of 18 and 24; 25.9% were from 25 to 44; 21.9% were from 45 to 64; and 15.2% were 65 years of age or older. The gender makeup of the city was 47.9% male and 52.1% female. 2000 census As of the census of 2000, there were 9,840 people, 3,838 households, and 2,406 families residing in the city. The population density was . There were 4,100 housing units at an average density of . The racial makeup of the city was 80.80% White, 0.63% African American, 0.45% Native American, 0.50% Asian, 6.19% from other races, and 1.43% from two or more races. Hispanic or Latino of any race were 14.99% of the population. There were 3,838 households, out of which 31.9% had children under the age of 18 living with them, 45.3% were married couples living