A striking and historically significant first flight cover commemorating the inaugural trans-Atlantic airmail service between the Azores and France. The front bears a large illustrated blue cachet reading "Correio Aéreo / 1ª Expedição" (First Expedition) with a route map highlighting the Azores-Lisbon connection, accompanied by the printed red-and-blue "First Flight / Trans-Atlantic / By Air Mail / Par Avion" label featuring a flying boat vignette. Franked with two Portugal 1$10 "Os Lusíadas" stamps (Scott 553 or similar), tied by Correio cancel dated May 1939. Addressed to J. Perkins, Newark, N.Y., U.S.A. The back carries a clear Marseille-Gare transit backstamp dated 20/22 May 1939, confirming the French routing. Cover shows light toning and age-appropriate wear consistent with 85+ years; overall a very presentable and desirable piece for trans-Atlantic airmail or Portuguese aviation history collectors.