Johnson County began the 20th century with about 18,000 people. It grew slowly until World War II, reaching a population of about 33,000 by 1940. After the war, suburban expansion quadrupled the population so that by 1960 over 143,000 people lived in the County. As of the 2000 census, Johnson County is home to 530,000 individuals.
Created in 1855 and organized in 1857, Johnson County was one of the first 33 counties in Kansas. Located near the twin cities of Kansas City, Kansas and Missouri, it contains 477 square miles, or 307,200 acres. Since the original establishment of the Shawnee Methodist Mission in 1839, Johnson County has developed into a complex mixture of urban and rural areas.
County government was established in Kansas to carry out state prescribed functions at the local level; that is, to act as an administrative agent for the state in such matters as tax assessment and collection, registration of motor vehicles, and record keeping. Also, as a local government, the County has assumed responsibility for provision of a wide variety of local services such as roads, public safety, health, environment, parks and recreation, planning and zoning, airports, library and civil defense.
The seven-member Board of County Commissioners is Johnson County's chief governing and policy-making body. County Commissioners are elected to four-year terms by the residents in districts that are roughly equal in population.
There are 30 departments, offices and agencies and more than 4,000 employees in Johnson County Government. Together they provide a variety of services.