Johnson County is a county located in western portion of the U.S. state of Missouri. As of the 2010 census, the population was 52,595 with a 2018 estimate of 53,652. Its county seat is Warrensburg. The county was formed December 13, 1834 from Lafayette County and named for Vice President Richard M. Johnson.
According to the U.S. Census Bureau, the county has a total area of 833 square miles (2,160 km), of which 829 square miles (2,150 km) is land and 3.9 square miles (10 km) (0.5%) is water.
As of the census of 2000, there were 48,258 people, 17,410 households, and 11,821 families residing in the county. The population density was 58 people per square mile (22/km²). There were 18,886 housing units at an average density of 23 per square mile (9/km²). The racial makeup of the county was 90.12% White, 4.33% Black or African American, 0.65% Native American, 1.43% Asian, 0.13% Pacific Islander, 1.29% from other races, and 2.05% from two or more races. Approximately 2.92% of the population were Hispanic or Latino of any race.
There were 17,410 households out of which 35.10% had children under the age of 18 living with them, 55.90% were married couples living together, 8.50% had a female householder with no husband present, and 32.10% were non-families. 22.70% of all households were made up of individuals and 7.10% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.07.
In the county, the population was spread out with 25.10% under the age of 18, 20.20% from 18 to 24, 27.60% from 25 to 44, 17.80% from 45 to 64, and 9.30% who were 65 years of age or older. The median age was 28 years. For every 100 females there were 101.90 males. For every 100 females age 18 and over, there were 100.40 males.
The median income for a household in the county was $35,391, and the median income for a family was $43,050. Males had a median income of $28,901 versus $21,376 for females. The per capita income for the county was $16,037. About 9.50% of families and 14.90% of the population were below the poverty line, including 15.20% of those under age 18 and 10.80% of those age 65 or over.
Johnson County Missouri neighborhoods include: Bristle Ridge, Brookside Place, Cayhill, Claymont, Clover Creek Estates, Country View, Hawthorne Blvd, Iron Horse, Lake Ridge, Mi Vecindario, Nw 1050, NW 121st Rd, South Heights/South Hills, Stonehill, SW 101st Rd, Warrensburg, W Market Street, W Young – W North