Constant wars in Europe took it's toll. Even after the creation of the United States, wars continued between England, it's allies and the French and their allies.

As those finally cooled down, world war breaks out.

Add the large are of land that makes up the U.S. with the large amount of resources easily available, and a unique for its day interstate trade system you have a good recipe for quick advancement. Lets not forget many bright minds from Europe migrated to the US.

How do you mean that question? The USA is a country (or a community of countries) which is quite big in size, natural resources and population compared to single European countries. I don't think you would just mean that it's bigger. If you compare countries of today as GDP per capita, then the USA has a good place, but European nations are surrounding her.

In any way the natural resources per capita are very much larger for the USA than for most European countries (except maybe Norway). Particularly Oil and soil per capita. After the oil boom (coal no longer beeing the major source of energy) of the 20th century the lack of European oil (of the time) would constitute a big advantage for oil-rich countries - as the US.