On 20 May, scheduled Atlantic service opened, with Capt. La Porte in the Yankee Clipper departing from Port Washington for Marseilles, carrying mail only. La Portes’s flight went smoothly, and all stations and facilities performed well. Because there were large numbers of first day air mail covers on these early flights, an unusual task became necessary.
ボーイング（Boeing）314飛行艇クリッパーClipper；鳥飼行博研究室
Yankee clipper hi-res stock photography and images - Alamy
Yankee clipper 1930s hi-res stock photography and images - Alamy
The Story of the Yankee Clipper's Maiden Voyage Across the Atlantic - Ghosts of Baltimore
History of flight - Airmail, Airlines, US
Pan Am Historical Foundation - Page #1
ボーイング（Boeing）314飛行艇クリッパーClipper；鳥飼行博研究室
Pan Am Historical Foundation - Page #1
Pan American inaugural air mail flight: Yankee Clipper, Southern route, 1939 [part 1] - Pan American World Airways Records - Digital Collections
Yankee Clipper Branch Grand Rapids Public Library
Pan Am's roots grew in Port Washington - Newsday
