The NC-4 was a Curtiss NC flying boat that was the first aircraft to fly across the Atlantic Ocean, albeit not non-stop. The NC designation was derived from the collaborative efforts of the Navy (N) and Curtiss (C). The NC series flying boats were designed to meet wartime needs, and after the end of World War I they were sent overseas to validate the design concept.

The aircraft was designed by Glenn Curtiss and his team, and manufactured by Curtiss Aeroplane and Motor Company, with the hull built by the Herreshoff Manufacturing Corporation in Bristol, Rhode Island.

In May 1919, a crew of United States Navy and US Coast Guard aviators flew the NC-4 from New York State to Lisbon, Portugal, over the course of 19 days. This included time for stops of numerous repairs and for crewmen's rest, with stops along the way in Massachusetts, Nova Scotia (on the mainland), Newfoundland, and twice in the Azores Islands. Then its flight from the Azores to Lisbon completed the first transatlantic flight between North America and Europe, and two more flights from Lisbon to northwestern Spain to Plymouth, England, completed the first flight between North America and Great Britain. This accomplishment was somewhat eclipsed in the minds of the public by the first nonstop transatlantic flight, made by the Royal Air Force pilots John Alcock and Arthur Whitten Brown two weeks later.