|Elizabeth Taft Murphy. Maryjane Hooper Town (Editor). I Remember, Do You? A nostalgic look at yesterday From the Twenties--to the Fifties. Ideals Publishing Corp., 1973.
Charles Lindbergh piloted the first flight with this aircraft type in 1931. I suspect that the photo above is of this inaugural flight.
According to the Wikipedia entry (which incorrectly designates the 80V as the Caribbean Clipper):
"The S-40 was Pan American's first large flying boat. The American Clipper served as the flagship of Pan Am's clipper fleet and this aircraft model was the first to earn the popular designation of "Clipper" or "Pan Am Clipper". The three S-40s served without incident during their civilian lives, flying a total of over 10 million miles. They were turned over to the US Navy during World War II and were used as trainers for four-engined flight instruction. All three of the S-40s were eventually retired and scrapped starting in 1943."