The lightbulb.. a joint effort globally, and if anything, English/Scottish/French. But America knew how to "Market" it (as always) and defeat rivals in its implementation. (See wikipedia on lightbulb history). Which I think summarises the US involvement in many situations - capitalising on the efforts of worldwide inventors (who in those days were often British, or French, or Canadian as much as the US, but didnt have the wherewithal to implement them).
Transistors were as much German, as American.
Nuclear Power was German expertise, and history as follows :
"On June 27, 1954, the world's first nuclear power plant to generate electricity for a power grid started operations at Obninsk, USSR. The reactor was graphite moderated, water cooled and had a capacity of 5 megawatts (MW). It produced 5 megawatts (electrical), enough to power 2,000 homes.
The world's first commercial nuclear power station, Calder Hall in Sellafield, England was opened in 1956, a gas-cooled Magnox reactor with an initial capacity of 50 MW (later 200 MW).
The Shippingport Reactor (Pennsylvania, 1957), a pressurized water reactor, was the first commercial nuclear generator to become operational in the United States."
(so worldwide again)
....and so it goes on.
American involvement is in implementation of such things, therefore, but not really especially in the innovation (which seems spread around a whole host of western and far eastern countries). Certainly not in comparison with the size and resources of the country.