Greenfield is a city in Hancock County, Indiana, United States, and is part of the Indianapolis metropolitan area. The population was 20,602 at the 2010 census. The city is the county seat of Hancock County, and lies in Center Township.
Greenfield was a stop along the Pittsburgh, Cincinnati, Chicago and St. Louis Railroad that connected Pittsburgh to Chicago and St. Louis. It is also home to the global headquarters of Elanco.
Hancock County was created on March 1, 1828, and named for John Hancock, the first person to sign the Declaration of Independence. The town of Greenfield was chosen as the county seat on April 11, 1828. The Commissioners announced, "The seat of Justice of Hancock County shall be known and designated by the name and title of Greenfield." The population of the county at that time was 400.