Hyde Park Township is a former civil township in Cook County, Illinois, United States that existed as a separate municipality from 1861 until 1889 when it was annexed into the city of Chicago. Its borders are Pershing Road (formerly 39th Street) on the north, State Street on the west, Lake Michigan and the Indiana state line on the east, and 138th Street and the Calumet River on the south. This region comprised most of what is now known as the South Side of Chicago.