1787: On July 16 , Framers of the Constitution created a bicameral legislature in which the Senate represents all states equally, while the House represents states in proportion to their respective populations.
1790: On December 6, Congress began a ten-year residence in Philadelphia, pending construction of a national capital in Washington, DC.
1794: On February 28, the Senate declared void the election of Albert Gallatin of Pennsylvania, the first contested election in Senate history. The Pennsylvania state legislature elected Gallatin to the United States Senate and he took the oath of office on December 2, 1793, but a petition filed with the Senate on that day alleged that Gallatin failed to satisfy the Constitutional citizenship requirement. On February 28, 1794, the Senate determined that Gallatin did not meet the citizenship requirement and declared his election void.
1795: The Senate approved Jay's Treaty on June 24.
1795: In December of 1795 the Senate opened its legislative sessions to the public. The previous year, the Senate held its first public session to determine whether to seat Albert Gallatin, senator-elect from Pennsylvania, and voted to end the practice of holding legislative sessions behind closed doors.
1795: On December 15, John Rutledge became the first Supreme Court nominee to be rejected by the Senate.
1797: On March 25, the President exercised his right, for the first time, to call an "extraordinary session" of Congress.
1797: William Blount of Tennessee became the first senator to be expelled on July 8.
1798: The Senate convened its first impeachment trial—of former Senator William Blount—on December 17.
1800: The Senate took up residence in the north wing of the unfinished Capitol in Washington, D.C. on November 17, and achieved its first quorum in the new national capital on November 21.
1802: On January 5, the Senate permitted admission of stenographers and note takers to the chamber floor.
1804: On March 12, the Senate convicted Federal Judge John Pickering and removed him from office, the first conviction following an impeachment trial.
1805: Vice President Aaron Burr delivered his farewell address to the Senate on March 2, while under indictment for the murder of Alexander Hamilton in a duel.
1807: On November 4, the Senate created a 3-member committee to audit and control the contingent expenses of the Senate, as proposed by Senator John Quincy Adams.
1814: Secretary of the Senate Samuel A. Otis died on April 22, having served as secretary for twenty-five years without missing a day on the job.
1814: During the War of 1812, British troops set fire to the Capitol building on August 24.
1816: The Senate established its system of permanent (standing) committees.
1818: The Senate swore in a 28-year-old member on November 16, violating the Constitution's requirement that senators be at least 30 years old. John H. Eaton (R-TN) still holds the record for the youngest senator.
1819: On December 6, the Senate occupied its newly reconstructed chamber that will serve as its home until 1859.
1820: On March 5, the Senate agreed to the "Missouri Compromise."
1824: The first issue of Register of Debates in Congress appeared on December 6, providing the first consistent coverage of Senate debates.
1824: On December 9, the Senate received the Marquis de Lafayette, who was given a seat of honor to the right of the presiding officer.
1825: On March 9, the Senate defeated a treaty with Colombia on suppression of the African slave trade.
1826: Funeral services for Senator John Gaillard of South Carolina were held in the Senate Chamber, with burial at Congressional Cemetery in Washington, D.C., representing the first public payment of funeral expenses for a senator who died in office.
1827: On December 17, the Senate directed its secretary to "cause seats to be prepared for the accommodation of the Reporters of the proceedings of the Senate." Reporters recording the proceedings for the Register of Debates in Congress had complained that their inability to hear distinctly resulted in numerous errors producing "great anxiety among those whose interests seemed likely to be affected."
1829: The Senate appointed its first page on December 7–nine-year-old Grafton Hanson, the grandson of Senate Sergeant at Arms Mountjoy Bayly.
1833: On March 19, the Senate returned to an earlier practice of electing committees by ballot of all members.
1834: On March 28, the Senate "censured" President Andrew Jackson for usurping congressional power. When Jackson's allies regained control of the Senate in 1837, they "expunged" the censure resolution.
1834: For the first time, on June 24, the Senate rejected a cabinet nomination—that of Roger Taney to be treasury secretary.
1835: On December 7, the Senate for the first time organized its committee system on the principle that the majority party should chair the major committees and control a majority of the seats on most panels.
1836: The Senate reserved one-third of its chamber's circular gallery on February 17 for the exclusive use of women.
1836: On March 15, the Senate confirmed Roger B. Taney as Chief Justice of the United States.
1841: The Senate conducted its first continuous filibuster on March 5, over the issue of dismissal of the printers of the Senate. The filibuster continued until March 11. The first extended filibuster, debating the establishment of a national bank, began on June 21 and lasted fourteen days.
1841: On July 8, the Senate amended Rule 47, removing reporters from the floor of the Senate chamber and placing them in the eastern gallery, then after known as the "press gallery."
1845: David Levy Yulee (D-FL) became the first Jewish senator to serve in the U.S. Senate on July 1.
1846: Members began to sit together in the Senate chamber according to party affiliation.
1846: The Senate began to make committee assignments based on recommendations of its political party caucuses rather than separate balloting of the full Senate.
1847: On December 3, the Senate chamber was lit with gas for the first time, providing "light enough to write by and read the finest print in any part of the chamber."
1848: The Senate arrested New York Herald correspondent John Nugent on March 26, in a futile effort to get him to reveal who leaked the still-secret treaty ending the war with Mexico. After several weeks of confinement in the Committee on Territories room, with evening trips to the Sergeant-at-Arm's home for dinner and a night's sleep, Nugent was set free on April 28.
1850: Senator Daniel Webster delivered one of the most notable speeches in Senate history on March 7. His classic three-hour oration set forth a defense of the Union and called on northerners to respect slavery in the South. Moderates in all sections praised his remarks, while northern abolitionists charged he had sold his soul to the devil.
1853: The Senate readopted Rule 34 on December 12, specifying for the first time the number of members specifically assigned to each committee.
1855: The Senate allowed its major committees to hire clerical staff.
1856: Senator Charles Sumner delivered his "Crime Against Kansas" speech on May 19, prompting the violent attack on his person by Representative Preston Brooks on May 22.
1859: The Senate occupied its current chamber for the first time on January 4.
1859: On September 16, Senator David Broderick became the first and only sitting senator to die in a duel.
1861: Jefferson Davis delivered his farewell address to the Senate on January 21 before leaving the chamber to become president of the Confederacy.
1864: On January 25, the Senate adopted a rule requiring senators and the Secretary of the Senate to take a loyalty oath.
1866: The Senate passed legislation on July 25, regulating election of senators by state legislatures.
1867: On March 6, in a move toward greater institutional efficiency, the Senate created a Committee on Appropriations , so that legislative committees would no longer be responsible for appropriating as well as authorizing funds.
1867: The Senate approved the Alaska purchase treaty on April 9.
1868: The Andrew Johnson impeachment trial began on March 30, and ended on May 16 when the Senate acquitted President Johnson by a one-vote margin.
1870: On February 23, Hiram Revels of Mississippi presented his credentials. He was sworn into office on February 25, becoming the first African American senator.
1871: In response to a growing number of contested elections, on March 10 the Senate created a Committee on Privileges and Elections to handle these contentious and often complex disputes. Four days later, the Senate sent to the committee pending cases from Alabama, Georgia, North Carolina, and Texas.
1871: The Senate established its own library on August 1, independent of the Library of Congress, and appointed its first librarian, George S. Wagner.
1873: The first Congressional Record was published on March 4.
1875: On March 4, seven years after the Senate acquitted him in an impeachment trial, Andrew Johnson became the first former president to serve as a senator .
1876: The Senate acquitted Secretary of War William Belknap on August 1. Belknap is the only cabinet officer ever impeached.
1877: To allow all members of each party to sit together in the chamber, on March 5 the Senate began the practice of moving desks according to party division rather than keeping an equal number of desks on each side of the center aisle.
1879: On February 14, Blanche K. Bruce became the first African American to preside over the Senate.
1880: The Senate adopted the "Anthony Rule" on February 5, allowing senators to speak no more than five minutes on certain measures before voting. This was the Senate's first effort to add a cloture provision to its rules.
1881: On January 14, the Senate agreed to "cause a telephone to be placed at some convenient point, for the use of the Senate, in connection with the general telephone system of the city of Washington."
1884: For the first time, the Senate provided all members with clerical staff.
1884: On July 5, the Senate directed the Sergeant at Arms and the Architect of the Capitol to rent suitable rooms outside the Capitol for committees and subcommittees–they decided on the Maltby Building.
1888: On February 22, the tradition of the reading of George Washington's farewell address began. It became an annual event beginning in 1893.
1895: Assistant Doorkeeper Isaac Bassett died on December 18. Bassett began his Senate service in 1831 as a page and after 1860 became widely identified as keeper of the Senate's historical lore.
1900: On April 6, the Senate revised Rule I to allow for appointment of a presiding officer by the president pro tempore or another senator in the event of the vice president's death.
1903: The Senate Democratic Conference began keeping minutes of its closed-door meetings on March 16.
1904: On April 28, Congress authorized construction of a fireproof Senate office building.
1906: On February 17, novelist David Graham Phillips' "Treason of the Senate" series began publication in Cosmopolitan magazine. This investigative series detailed the relationship between senators and corporate interests, and was one factor leading to the direct election reform of the Progressive era.
1906: Congress authorized funds on February 26 for construction of a "subway" connecting the Capitol and Senate office building.
1906: On noon of July 31 the cornerstone was laid for what is now known as the Russell Senate Office Building.
1907: Charles Curtis of Kansas became the first Native American senator. Curtis was part Kaw Indian, his mother was the granddaughter of Kansa-Kaw Chief, White Plume.
1909: The Senate opened its first permanent office building, which in 1972 was named in honor of Senator Richard B. Russell (D-GA).
1913: On March 5, John W. Kern became the first officially designated Democratic floor leader.
1913: The Constitution was amended (Seventeenth Amendment) to provide for direct popular election of senators, ending the system of election by individual state legislatures.
1914: The Senate adopted a rule on March 9 forbidding smoking on the floor of the Senate because Senator Ben Tillman, recovering from a stroke, found the smoke irritating.
1917: President Woodrow Wilson delivered his "Peace Without Victory" speech in the Senate Chamber on January 22. He returned two years later to deliver the Treaty of Versailles to the Senate.
1917: The Senate adopted a rule (cloture) to limit filibusters.
1918: On November 5, Jeannette Rankin became the first woman of a major party to run (unsuccessfully) for a Senate seat. Rankin was currently serving as a member of the House of Representatives.
1920: On March 1, Public Law 66-190 became the first statute to be printed on paper instead of parchment.
1920: On November 2, Warren G. Harding became the first incumbent senator to be elected president of the United States.
1922: On October 3, Rebecca Felton of Georgia was appointed to fill a vacant Senate seat, becoming the first female senator. She took the oath of office on November 21, and served just 24 more hours before relinquishing the seat to duly elected senator Walter George.
1923: On October 22, the Committee on Public Lands and Surveys began a series of hearings to investigate the leasing of government oil reserves in Wyoming to oil men and developers. This became known as the "Teapot Dome" investigation.
1925: Senate Republicans officially designated their floor leader for the first time–Charles Curtis (R-KS)–on March 5.
1925: Harlan Fiske Stone became the first Supreme Court nominee to appear before the Senate Judiciary Committee.
1926: Smith W. Brookhart (R-IA) became the first previously seated senator to be unseated following a recount of election ballots.
1927: In McGrain v. Daugherty, the U.S. Supreme Court firmly established the general power of congressional committees to compel testimony from witnesses.
1927: On December 5, Democratic Leader Joseph T. Robinson (D-AR) started the tradition of party floor leaders sitting at the front-row, center-aisle desk in the Senate chamber.
1928: Octaviano Larrazolo (R-NM) became the first Hispanic senator on December 7.
1929: The first radio broadcast from the Senate chamber occurred on March 4, in connection with the vice presidential inauguration ceremony.
1932: On January 12, Hattie Ophelia Wyatt Caraway (D-AR) became the first woman elected to the Senate. Reelected twice, she served until 1945.
1933: On March 9, the Senate passed the Emergency Bankng Act after only several hours of debate.
1935: On July 1, the Senate established the office of the Senate Parliamentarian and promoted journal clerk Charles Watkins to the new position. He continued as journal clerk for two more years, serving in both positions. Watkins remained parliamentarian until his retirement in 1964.
1935: Senator Huey P. Long (D-LA) was assassinated in Baton Rouge, Louisiana, on September 10.
1937: On March 25, 1937, the Senate agreed to transfer its historical records to the newly opened National Archives. Previously, Senate clerks had kept official records in the Capitol's attic and basement store rooms where they became victim to vermin, moisture, and souvenir hunters.
1937: On August 13, Vice President John Nance Garner announced a policy of priority recognition to the majority leader and and then the minority leader in the Senate chamber.
1939: The Senate passed a resolution providing that "the Chaplain shall open each day's session of the Senate with prayer."
1939: Columbia Pictures released Frank Capra's film Mr. Smith Goes to Washington . Forty-five senators attended a world premiere of the film on October 17, held at Washington's Constitution Hall.
1941: On March 1, a Senate resolution created The Truman Committee, the Special Committee to Investigate the National Defense Program.
1941: On December 26, Congress held a joint meeting in the Senate chamber for an address by British Prime Minister Winston Churchill.
1943: On October 19, Hattie Caraway (D-AR) became the first woman to preside over the Senate.
1945: President Harry S. Truman addressed the Senate on the United Nations charter on July 2.
1946: President Harry S. Truman signed the Legislative Reorganization Act, which reformed the committee system, sweeping away obsolete committees, eliminating redundancy in committee work, and establishing an effective congressional staff system.
1947: Implementing aspects of the Reorganization Act, each member and committee hired professional staff for the first time.
1947: On January 2, the Senate established the Committee on Armed Services.
1947: On March 18, 1947, the Senate Rules Committee gave press gallery accreditation to Louis R. Lautier, making him the first African-American reporter to sit in that gallery in seventy years.
1948: Margaret Chase Smith (R-ME) became the first woman elected to both houses of Congress.
1948: On November 2, Russell Long of Louisiana became the first senator to win a seat previously occupied by both his father (Huey Long) and mother (Rose Long).
1949: A major remodeling project began in the Senate chamber.
1950: On February 9, in a speech in Wheeling, West Virginia, Senator Joseph McCarthy (R-WI) first raised charges that Communists had infiltrated federal government agencies.
1950: On June 1, Senator Margaret Chase Smith (R-ME) delivered her "Declaration of Conscience" speech, attacking–without naming–Senator Joseph McCarthy for his anti-communist tactics, referring to them as "vilification" and "smear."
1953: William Knowland became the youngest Majority Leader in Senate history, at age 45. Lyndon Baines Johnson became the youngest Democratic leader in Senate history, also at age 45.
1954: On April 22, the Senate began a 55-day series of "Army-McCarthy" hearings . Television transformed the hearings into a national spectacle.
1954: On November 2, Hazel Hempel Abel (R-Nebraska) became the first woman senator to succeed another woman (Eva Bowring).
1954: The Senate "condemned" Senator Joseph McCarthy on December 2.
1955: On January 21, the Senate paid tribute to seven employees, each with more than fifty years of service, including Charles Watkins (Parliamentarian and journal clerk since 1904), Paul Johnson (restaurant head waiter since 1900), Arthur Cook (assistant Architect of the Capitol, 1897), Charles Alden (assistant superintendent of the Senate office buildings, 1900), Lillian Taylor (architectural clerk, 1901), James Preston (Senate registration clerk, 1897), and James Murphy (chief reporter of debates since 1896).
1956: The Senate Republican Policy Committee commenced weekly luncheon meetings on January 17.
1957: On August 28-29, Senator J. Strom Thurmond of South Carolina delivered the longest speech in Senate history. Filibustering against the 1957 Civil Rights Act, Thurmond spoke for a record-breaking 24 hours 18 minutes.
1957: Five senators were chosen as "most outstanding" by a special Senate committee, chaired by Senator John Kennedy. When special portraits were commissioned for the Senate Reception Room, they became known as the "Famous Five."
1959: The Senate unveiled portraits of the Famous Five in the Senate Reception Room: John C. Calhoun, Henry Clay, Daniel Webster, Robert La Follette, Sr., and Robert A. Taft, Sr.
1959: Hiram L. Fong (R-HI) became the first senator of Chinese-American ancestry on July 29.
1964: On June 10, the Senate ended a lengthy filibuster, allowing for passage of the historic Civil Rights Act of 1964.
1965: The Select Committee on Standards and Conduct was created on July 9, forerunner of the current Select Committee on Ethics.
1968: Senator Robert F. Kennedy died from the effects of an assassin's bullet on June 6, while campaigning for the Democratic presidential nomination.
1968: On September 6, Senator Margaret Chase Smith of Maine missed her first roll call vote in thirteen years. Since 1955 she had cast 2,941 consecutive roll call votes. The missed vote was due to the Senator's hospitalization in New York.
1971: Paulette Desell and Ellen McConnel, both sixteen years old, became the Senate's first female pages.
1972: Supreme Court decides Gravel vs. U.S. , providing immunity from prosecution for Senator Mike Gravel who read the secret "Pentagon Papers" into the public record. Decision based on the Constitution's "Speech and Debate Clause."
1973: The Senate Select Committee on Presidential Campaign Activities (the Watergate Committee) opened public hearings.
1974: Television records Vice President Nelson Rockefeller being sworn into office in the Senate Chamber.
1974: The Senate Budget Committee was established.
1974: The Senate provided that the "Daniel Webster Desk" be assigned to the senior senator from New Hampshire.
1975: The Senate voted to open committee meetings to the public.
1975: Senate revised cloture rule to allow three-fifths of the senators voting to end debate rather than two-thirds.
1975: Senator Mike Mansfield of Montana set the record for longest-serving Majority Leader, having held that post for sixteen years.
1975: Senate opened all committee meetings to the public.
1976: The Old Senate Chamber is restored and reopened for the National Bicentennial.
1977: The [Frank] Church Committee investigation of the CIA led to creation of the Senate Intelligence Committee.
1977: Senate Select Committee on Ethics is established, which acopted the "Code of Official Conduct for Members, Officers, and Employees of the United States Senate."
1978: Senate debates on the Panama Canal Treaty broadcasted over National Public Radio.
1978: Senate began requiring public financial disclosure by all members, candidates, officers, and certain employees.
1980: Senator Robert C. Byrd began a series of hour-long lectures to the Senate on the institution's history and traditions. By 1989, he had delivered more than one hundred addresses.
1981: First change in majority party control in twenty-six years.
1982: The Senate opened its third office building, named in honor of Senator Philip A. Hart of Michigan.
1983: Terrorists explode a bomb at 11:00 p.m. on the second floor of the U.S. Capitol, outside the Senate chamber, causing $250,000 in damage.
1985: Jo-Anne Coe became the first female Secretary of the Senate.
1986: Regular television coverage (C-Span 2) of Senate floor proceedings began.
1987: The Senate participates in a joint committee to investigate the Iran-Contra affair.
1987: The Senate established the Office of Senate Security, to replace the Office of Classified National Security Information.
1987: C. Abbott Saffold became the first female Democratic Party Secretary.
1989: The Senate convened in the Old Senate Chamber on April 6, 1989, to celebrate its 200th birthday.
1991: Martha Pope became the first female Senate Sergeant at Arms . In 1994, Pope became secretary of the Senate, the first woman to serve in both positions.
1993: On January 5, Carol Moseley-Braun of Illinois became the first African-American female to serve in the U.S. Senate.
1993: The Supreme Court ruled in Walter Nixon v. United States that the Senate's power to try impeachments is not subject to judicial review.
1995: Senate Republicans adopted a rule limiting the party's committee chairmen to a six-year term.
1995: Senator Nancy Kassebaum became first woman to chair a major standing committee. (Senator Hattie Caraway chaired the Committee on Enrolling Bills in 1933.)
1995: Senate Republicans adopted a term limit on committee chairships, limiting committee chairs and ranking members to a six-year term.
1995: The Senate launched its first home page on the World Wide Web—www.senate.gov.
1995: Elizabeth Letchworth became the first female Republican Party Secretary.
1996: Senate employees gained collective bargaining rights under the 1995 Congressional Accountability Act.
1997: The Senate's membership, for the first time, included nine women.
1998: Senator John Glenn returned to space aboard the Space Shuttle Discovery .
1999: The Senate held an impeachment trial of President William Clinton. Trial began on January 14, and the Senate voted on articles of impeachment, ending the trial with acquittal, on February 12.
1999: The Senate Commission on Art created the Senate Leadership Portrait Collection to honor presidents pro tempore and majority and minority leaders. Interest in memorializing Senate leaders had been sparked by the Leader's Lecture Series, in which former leaders share their insights with current and past members of the Senate. Senator Howard Baker was the honored guest at the leader's lecture in 1998 when he spoke about his years as majority leader. A portrait of Baker, painted by Herbert Elmer Abrams, was donated to the Senate by the Everett M. Dirksen Congressional Center in 2000, and became the first portrait acquired for the new series.
1999: On November 10, a Senate session was staffed entirely by women for the first time.
2000: The Senate approved the addition of two new portraits, to join the Famous Five in the Senate Reception Room, creating The Famous Seven.
2000: On November 7, Hillary Rodham Clinton became the first "First Lady of the United States" to be elected to the Senate.
2001: Following the 2000 election, the Senate was divided evenly–50/50–between the two parties, Republicans and Democrats. From January 3 to January 20, the Democrats held the majority, thanks to the tie-breaking vote of Vice President Al Gore. When Dick Cheney became Vice President on January 20, 2001, the Republicans regained majority status and held it until June 6, 2001, when Senator James Jeffords' switch from Republican to independent status returned the majority to the Democrats.
2001: Four more women became senators on January 3, bringing the total to a record-setting thirteen.
2001: Alfonso E. Lenhart became the first African American to serve as Senate Sergeant at Arms.
2001: A terrorist attack on the World Trade Center in New York and the Pentagon forced a temporary evacuation of the U.S. Capitol and Senate office buildings.
2001: On October 17, two days after a letter containing anthrax was opened in the office of Senator Tom Daschle, Senate leadership closed the Hart Senate Office Building. The building remained closed for remediation for three months, displacing fifty senators and hundreds of staff. The building reopened on January 22, 2002.
2002: On September 6, the United States Senate and the House of Representatives met in a commemorative joint session in New York City's Federal Hall. A tribute to the heroes and victims of September 11, 2001, the meeting also marked the return of Congress to the location of its first home. The first U.S. Congress met in an earlier Federal Hall from March 4, 1789 to August 12, 1790, before moving to Philadelphia for ten years while building its permanent home in Washington, D.C.
2002: On October 25, Senator Paul Wellstone of Minnesota, along with his wife, daughter and three staff members, died in a plane crash while on the campaign trail.
2002: On December 2, Senator Frank Murkowski resigned to become Governor of Alaska. On December 20, Governor Murkowski appointed his daughter, Lisa Murkowski, to fill the vacancy caused by his own resignation. They became the first father-daughter combination to serve in the Senate.
2002: Senator Strom Thurmond celebrated his 100th birthday on December 5, setting a new record as the only sitting senator to reach the century mark. Thurmond died seven months later.
2002: Following Senator Trent Lott's resignation as Republican leader on December 20, Senator William Frist of Tennessee was elected Republican leader by telephone conference call on December 23.
2004: Portraits of Senators Robert Wagner of New York and Arthur Vandenberg of Michigan were added to the Senate Reception Room, joining the " Famous Five."
2005: On May 24, a newly commissioned portrait of former Majority Leader George J. Mitchell was unveiled and added to the Senate Leadership Portrait Collection established in 1999.
2005: A newly commissioned portrait of Maine Senator Margaret Chase Smith was unveiled in the Capitol's Old Senate Chamber on October 18.
2006: On January 18, Senator Robert Menendez (D-NJ) took the oath of office, having been appointed to a vacant seat, and became the sixth Hispanic American known to have served in the U.S. Senate.
2006: On July 25, a newly commissioned portrait of former Majority Leader Robert J. Dole was unveiled and added to the Senate Leadership Portrait Collection established in 1999.
2007: On September 25, a newly commissioned portrait of Senator Robert C. Byrd , former majority leader of the Senate, was unveiled and added to the Senate Leadership Portrait Collection established in 1999.
2008: On April 22, a newly commissioned portrait of Senator Tom Daschle , former majority leader of the Senate, was unveiled and added to the Senate Leadership Portrait Collection established in 1999.
2008: On November 4, Senator Barack Obama of Illinois was elected as the 44th president of the United States, along with Senator Joseph Biden of Delaware as vice president. To date, fifteen senators had also served as president . Only twice before has a sitting senator been elected president–Warren G. Harding in 1920 and John F. Kennedy in 1960.