The US economic output surpassed that of Britain roughly in 1910. Militarily we weren’t ready for WW1 with the exception of our Navy. So I would say we had the complete set by 1920. The US had a very strong say at Versaille, 1919.
Our Navy, the so-called Great White Fleet was basically a cardboard fleet. A good description of it was in “Guns Of August” by Barbara Tuchman. She describes how weak those ships really were compared to say the English Dreadnoughts. I forget off hand when we built our first Dreadnought class battle ship. I found this an interesting read: http://www.navy.mil/navydata/ships/battleships/bbhistory.asp