Caption reads: “Dixie Clipper completes first transatlantic passenger flight / New York to Lisbon, Portugal, June 29, 1939 / Boeing B-314″.
This flight had left from Port Washington the day before, captained by R. O. D. Sullivan, with 22 passengers on board.
From Pan American’s “Historic First Flights of Pan American Clippers” series.

Boeing 314, Known As “Dixie Clipper”, Takes Off « Port Washington Aviation History // Aug 16, 2009 at 9:14 am
[...] See our post featuring artist John T. McCoy’s rendering of the Dixie Clipper here. [...]
Thanks for the clarification!