<P> No Tax or Duty shall be laid on Articles exported from any State . </P> <P> Until 1913, customs duties (tariffs) and excise taxes were the primary sources of federal revenue . During the War of 1812, Secretary of the Treasury Alexander J. Dallas made the first public proposal for an income tax, but it was never implemented . The Congress did introduce an income tax to fund the Civil War through the Revenue Act of 1861 . It levied a flat tax of three percent on annual income above $800 . This act was replaced the following year with the Revenue Act of 1862, which levied a graduated tax of three to five percent on income above $600 and specified a termination of income taxation in 1866 . The Civil War income taxes, which expired in 1872, proved to be both highly lucrative and drawing mostly from the more industrialized states, with New York, Pennsylvania, and Massachusetts generating about 60 percent of the total revenue that was collected . During the two decades following the expiration of the Civil War income tax, the Greenback movement, the Labor Reform Party, the Populist Party, the Democratic Party and many others called for a graduated income tax . </P> <P> The Socialist Labor Party advocated a graduated income tax in 1887 . The Populist Party "demand (ed) a graduated income tax" in its 1892 platform . The Democratic Party, led by William Jennings Bryan, advocated the income tax law passed in 1894, and proposed an income tax in its 1908 platform . </P> <P> Before Pollock v. Farmers' Loan & Trust Co., all income taxes had been considered to be indirect taxes imposed without respect to geography, unlike direct taxes, that have to be apportioned among the states according to population . </P>

The powers of congress are found in article i section 8 of the constitution. answers.com