Please feel free to elaborate on when you feel America was a world power and support it with facts/arguments.

http://en.wikipedia.org/wiki/Income_..._United_States

Note: Section 3.1 history of top US tax rates.

From 1932 to 1981 the tax rate was 67% or higher for the top bracket.

Likewise for 1917-1921.

The only periods with tax rates lower than present were:

Pre-1913 (no federal income taxes),1925-1931 and 1988-1992.

Before 1913 the US was not a major international power, and from 1925-1931 you see the fiscal policies that shaped the great depression in action.

In 1988-1992 you have a brief dip below present day rates, that lead to a soaring national deficit which was brought under control by Clinton before again spiraling out of control under Bush (and likely getting even worse under Obama).