Riley county was one of the original 33 counties created by the Territorial Legislature on March 8, 1855, and was organized
 on September 17, 1855, by Thomas Reynolds; C. R. Mobley; and Clay Thompson. It was named for
 Major General Bennet C. Riley, commander of Fort Leavenworth, and contains the cities of Leonardville, Randolph, Riley,
 Manhattan (part) and Odgen.

 In 1852 Camp Center was established near the junction of the Smoky Hill and Republican rivers. In 1853 the fort was
 renamed Fort Riley. The fort has been the major influence in the county's history. Today it is the home of the
 U. S. Army's First Division.

 The Methodist Church in Manhattan was organized in 1855. The Manhattan Congregational Church (1858) still uses its
 original building. Shortly after the founding of the city of Manhattan, George Park suggested the establishment of an
 agricultural school. Begun as a Methodist sponsored school in 1859, the state finally accepted the school into the system in
 1863 as one of the first land grant college in the United States under the Morrill Act. The first county fair was held in 1869.
 The first school district was formed countywide in 1858. The first schoolhouse was in Manhattan, 1859. The construction in
 1959-1963 of Tuttle Creek Dam and reservoir for flood control, inundated three Riley County towns, and caused the
 relocation of another. Randolph relocated one mile to the west.