Background: The Air Mail Act of 1925 (Kelly Act) authorized the postmaster general to contract for domestic airmail service with commercial air carriers. It also set airmail rates and the level of cash subsidies to be paid to companies that carried the mail. By transferring airmail operations to private companies, the government effectively would help create the commercial aviation industry. Various routes were designated and contracts for carrying the mail over these routes were then awarded to many different private air service companies. The Contract Air Mail routes became known as CAM's.

CAM-17: CAM-17 was awarded to National Air Transport. NAT was founded in 1925 by Clement M. Keys who selected Howard E Coffin as its chairman. In addition to CAM-3 air service, CAM-17 was inaugurated with both east and west flights on September 1, 1927 between Chicago IL and New York NY with an interim stop in Cleveland OH. Postal mail covers carried on the inaugural flight between each point of landing and take-off are collectible and are known as CAM-17 covers.

CAM-3

National Air Transport used Curtiss Carrier Pigeon bi-planes with Curtiss engines for this initial September 1, 1927 air service. The Carrier Pigeon bi-planes were built by the Curtiss Aeroplane Company founded by Glenn Curtiss and now controlled by Clement Keys.
Pilots flying different legs of this September 1st CAM-17 inaugural air service included, Frank H Burnside, Harry Chandler, William C Hopson, Leo J McGinn, SJ Short and Warren D Williams.

CAM-17: On February 9, 1934 the Post Office Department canceled all contracts of operators flying mail on routes within the US to become effective on February 19, 1934. The reason given by the Post Office was that there was suspicion that the mail carrying contracts had been awarded through collusion during the previous Administration.
Cancellation of the air mail contracts held by established pioneer airline companies was accompanied by an executive order from President Franklin D Roosevelt stating that the Army Air Corps should now carry the mail. Three territorial zones were established for the Air Corps mail operations, Newark NJ, Chicago IL and Salt Lake City UT. The eastern, central and western zones each had branch routes to other feeder cities. It was a difficult assignment for the Army Air Corps as they did not have enough planes and the ones they had, did not have the latest instruments, landing, navigation, or cockpit lights. One of the aircraft they used was the Keystone B-4 bi-plane.

Army Air Corps

New commercial air mail carrying contracts were made in May 1934 and the mail was again flown by private contractors over re-designated revised Post Office Department routes in late June 1934.

CAM-17: After the February 1934 cancellation and reinstatement of new commercial air mail carrying contracts over re-designed revised Post Office routes in late June 1934, United Air Lines began flying CAM-17 air mail from New York NY to Chicago IL.
United Aircraft and Transport Corporation had been formed on February 1, 1929 with the partnership merger of Boeing Air Transport and Pratt & Whitney. UAL began on July 1, 1931 as the holding company of four air carriers, Boeing Air Transport (CAM-18), Varney Air Lines (CAM-5), Pacific Air Transport (CAM-8) and National Air Transport (CAM-17). Each of these contributing airlines flew different types of aircraft when taken over by United. One such aircraft was the Stearman M-2 Speedmail.

UAL

UAL was organized as the "World's Largest Air Transport System."