Yesterday, a postal employee landed a gyrocopter on the Capital building lawn in Washington, D.C. He was carrying letters to members of Congress urging them to enact campaign finance reform. While this gentleman's political statement was certainly not authorized by his employer, the U.S. Postal Service (although he did have USPS decals on his aircraft), as Gizmodo noted in this post, the USPS once used gyrocopters, or "autogyros" as they were called back then, to deliver the mail. This late 1930's film from Eastern Airlines shows one of the company's autogyros delivering the mail between Philadelphia and Camden, N.J.
Autogyros are very interesting aircraft, and were a popular early alternative to helicopters. Although they resemble helicopters, the distinguishing feature is the main rotor. Helicopters use their main overhead rotor for lift, propulsion and directional control. Autogyros used their overhead rotor only for lift, relying on an airplane type propeller to pull or push the craft through the air, and control surfaces such as rudders for directional control. As a result, autogyros are much simpler, and thus were much cheaper to acquire, operate and maintain than early helicopters, but they could still take off and land in very small spaces.