The 40th United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C. from March 4, 1867, to March 4, 1869, during the third and fourth years of Andrew Johnson's presidency. The apportionment of seats in the House of Representatives was based on the 1860 United States census. Both chambers had a Republican majority. In the Senate, the Republicans had the largest majority a party has ever held. Major events March 30, 1867: Alaska Purchase February 24, 1868: Impeachment of Andrew Johnson May 16, 1868: President Johnson acquitted May 26, 1868: President Johnson acquitted again November 3, 1868: 1868 presidential election: Ulysses S. Grant (R) defeated Horatio Seymour (D) December 25, 1868: President Johnson granted unconditional pardons to all Civil War rebels January 20, 1869: Elizabeth Cady Stanton was the first woman to testify before Congress Major legislation Three Military Reconstruction Acts, continued: March 23, 1867, ch. 6, July 19, 1867, ch. 30, March 11, 1868, ch. 25, July 27, 1868: Expatriation Act of 1868, ch. 249, Constitutional amendments July 10, 1868: Fourteenth Amendment to the United States Constitution declared ratified February 26, 1869: Approved an amendment to the Constitution prohibiting the federal and state governments from denying a citizen the right to vote based on that citizen's "race, color, or previous condition of servitude", and submitted it to the state legislatures for ratification Amendment was later ratified on February 3, 1870, becoming the Fifteenth Amendment to the United States Constitution Treaty April 29, 1868: Treaty of Fort Laramie (1868), , signed February 16, 1869: Treaty of Fort Laramie (1868) ratified Territories organized July 25, 1868: Wyoming Territory organized, Sess. 2, ch. 135, Party summary The count below identifies party affiliations at the beginning of the first session of this Congress, and includes members from vacancies and newly admitted states, when they were first seated. Changes resulting from subsequent replacements are shown below in the "Changes in membership" section. During this Congress, Arkansas, Florida, Alabama, North Carolina, Louisiana, and South Carolina were readmitted to representation in both the Senate and the House. Georgia was readmitted with representation in the House only. Senate House of Representatives Leadership Senate President: Vacant President pro tempore: Benjamin Wade (R) Republican Conference Chairman: Henry B. Anthony Democratic Campaign Committee Chairman: James Rood