stagecoach and a DC 3, this strange photo has been revealed by Steve to be part of a 1949 advertisement

Steve found that this is from an advertisement that American Airlines ran in various magazines in 1949. This one is from the April 4, 1949 issue of Time.
The title reads "This month a grand old plane makes its last flight." The copy states that the DC-3 (21 passengers at 200 mph) was being replaced by the DC-6 (52 passengers at 300 mph) and the Convair CV-240 (40 passengers at 300 mph). The DC-4 (44 passengers at 227 mph) had been retired by the airline the year before.