Johnson County is a county in the U.S. state of Indiana. As of 2020, the population is 161,765. The county seat is Franklin. Johnson County is part of the Indianapolis-Carmel-Anderson metropolitan statistical area in Indiana.
According to the 2010 census, the county has a total area of 833.4 square kilometers (321.79 square miles), of which the land area is 829.9 square kilometers (320.43 square miles) (or 99.58%), 3.5 square kilometers (1, 36 square miles) (or 0.42%) ). is water.
Johnson County was founded in 1823. It is named after Indiana Supreme Court Justice John Johnson. This is likely John Johnson of Knox County, a delegate to the state’s Constitutional Convention who was appointed to the Supreme Court in 1816.