http://en.wikipedia.org/wiki/Income_tax_in_the_United_States :
Selected Historical income tax rates (1913–2011)
Partial History of
U.S. Federal Marginal Income Tax Rates
Income First Top Bracket
Year Brackets Bracket Rate Income Adj. 2011 Comment
1913 7 1% 7% $500,000 $11.3M First permanent income tax
1917 21 2% 67% $2,000,000 $35M World War I financing
1925 23 1.5% 25% $100,000 $1.28M Post war reductions
1932 55 4% 63% $1,000,000 $16.4M Depression era
1936 31 4% 79% $5,000,000 $80.7M
1941 32 10% 81% $5,000,000 $76.3M World War II
1942 24 19% 88% $200,000 $2.75M Revenue Act of 1942
1944 24 23% 94% $200,000 $2.54M Individual Income Tax Act of 1944
1946 24 20% 91% $200,000 $2.30M
1954 24 20% 91% $200,000 $1.67M
1964 26 16% 77% $400,000 $2.85M Tax reduction during Vietnam war
1965 25 14% 70% $200,000 $1.42M
1981 16 14% 70% $212,000 $532k Reagan era tax cuts
1982 14 12% 50% $106,000 $199k "
1987 5 11% 38.5% $90,000 $178k "
1988 2 15% 28% $29,750 $56k "
1991 3 15% 31% $82,150 $135k
1993 5 15% 39.6% $250,000 $388k
2003 6 10% 35% $311,950 $380k Bush era tax cuts
2011 6 10% 35% $379,150 $379k