Conversation so far:
How many aircraft did Glenn Curtiss's factory produce during World War 1?
The JN-4 and N-9 were some of the most famous products of the Glenn Curtiss company, and thousands were sold to the militaries of the US, Canada, and Britain.
How many employees did Glenn Curtiss's company employ in Buffalo during World War 1?
Civilian and military aircraft demand boomed, and the company grew to employ 18,000 workers in Buffalo and 3,000 workers in Hammondsport.
What year was the Glenn Curtiss NC designed?
In 1917, the U.S. Navy commissioned Glenn Curtiss to design a long-range, four-engined flying boat large enough for a crew of five.

Question: Where are the four NC flying boats located today?
Self-contained rewrite: Where are the four NC flying boats located today?