 After an intermittent series of government sponsored experimental flights between 1911 and 1918, domestic U.S. Air Mail was formally established as a new class of service by the Post Office Department on May 15, 1918, with the inauguration of the Washington–Philadelphia–New York route for which the first of special Air Mail stamps were issued.The exclusive transportation of flown mails by government operated aircraft came to an end in 1926 under the provisions of the "Kelly Act" which required the USPOD to transition to contracting with commercial air carriers to fly them over Contract Air Mail (CAM) routes to be established by the Department, although during the first half of 1934 the U.S. Army Air Forces temporarily took over the routes — with disastrous results — when all CAM contracts were summarily cancelled by President Franklin D. Roosevelt owing to the Air Mail Scandal.Domestic air mail became obsolete in 1975, and international air mail in 1995, as distinct extra fee services when the USPS began transporting all First Class long distance intercity mail by air on a routine basis.