A 1955 U.S. Patent for a "Constant Speed Regulator" was filed in 1950 by M-Sgt Frank J. Riley.[4] He installed his invention, which he conceived while driving on the Pennsylvania Turnpike, on his own car in 1948.[5] Another inventor named Harold Exline, working independently of Riley, also invented a type of cruise control, which he first installed on his own car and on cars belonging to friends of his.