1848
The Senate approved the Treaty of Guadalupe Hidalgo, ending the Mexican-American War. Under the terms of the treaty, Mexico ceded a vast amount of territory to the United States, including about 70 percent of present-day Arizona.
1850
The Senate passed the act organizing the New Mexico Territory, which included much of present-day Arizona. The act was the first of five known collectively as the Compromise of 1850.
1853
U.S. Minister to Mexico James Gadsden negotiated with Mexico leader Santa Anna to purchase more territory, including the remaining 30 percent of Arizona. This became known as the Gadsden Purchase.
1863
The Senate passed legislation organizing Arizona as a separate territory. Four days later, the president signed the bill.
1911
President William Howard Taft vetoed a joint resolution for the admission of Arizona to statehood because he objected to a provision in the Arizona constitution permitting the recall of judges. In December the people of the territory voted to remove the recall provision but after admission to statehood in 1912, the voters reinstated the provision.
1912
Arizona became the 48th state in the Union.
1912
Henry Fountain Ashurst of Prescott and Marcus Smith of Tucson presented their credentials, took the oath of office, and were seated as Arizona's first United States senators. Both had been elected by the state legislature on March 26. The senators then drew lots to determine their class assignments. Senator Ashurst drew Class 1, with a term to expire March 3, 1917. Senator Smith drew Class 3, with a term to expire March 3, 1915.
1914
Henry Fountain Ashurst became chairman of the Senate Committee on Indian Affairs, serving until 1919.
1925
Senator Henry Ashurst delivered George Washington's Farewell Address to the U.S. Senate, a Senate tradition dating to 1862.
1927
Carl Hayden of Phoenix, who had represented Arizona in the House of Representatives since 1912, began his Senate career. Hayden became Arizona’s longest-serving senator on December 11, 1955, surpassing Henry Ashurst’s total of 28 years, 9 months, and 7 days. Upon his retirement in 1969, Hayden had served in the Senate for 41 years and 9 months, and 30 days.
1930
A statue of John C. Greenway, a Rough Rider and military officer, sculpted by Guzon Borglum, was unveiled in the U.S. Capitol as Arizona's first contribution to the National Statuary Hall Collection. In 2015 Arizona replaced Greenway's statue with one of Barry Goldwater.
1933
Henry Fountain Ashurst became chairman of the Senate Committee on the Judiciary, serving until 1941.
1944
President Franklin D. Roosevelt signed the Servicemen's Readjustment Act of 1944, better known as the "GI Bill." Originally proposed by Senator Ernest William McFarland of Florence and unanimously passed by both the House and Senate, the legislation helped returning veterans pay for education and housing to re-enter civilian life.
1949
Joseph C. Duke of Bisbee, Arizona, was elected Senate sergeant at arms, serving from 1949 to 1953, and again from 1955 to 1965.
1949
Carl Hayden became chairman of the Senate Committee on Rules and Administration, serving until 1953.
1949
As chairman of the Joint Congressional Committee on Inaugural Ceremonies, Senator Carl Hayden accompanied President Harry Truman from the White House to the inaugural ceremonies at the Capitol.
1951
Senate Democrats elected Ernest McFarland as their floor leader and Conference chairman and as the Democratic Policy Committee chairman. McFarland held these posts until 1953. He was defeated for reelection to the Senate in 1952 by Barry M. Goldwater of Phoenix.
1954
Former senator Ernest McFarland was elected governor of Arizona and served from 1955 to 1959.
1955
Carl Hayden became chairman of the Senate Committee on Appropriations and held that position until 1969, becoming the committee's longest-serving chair.
1957
Senator Barry Goldwater delivered George Washington's Farewell Address to the U.S. Senate, a tradition dating to 1862.
1960
Senator Barry Goldwater published The Conscience of a Conservative, promoting a revival of conservatism.
1962
Former senator Henry Fountain Ashurst played the part of an elderly senator in the motion picture Advise and Consent.
1964
Senator Barry Goldwater won the Republican Party nomination for president of the United States but was defeated in November by the incumbent president, Lyndon B. Johnson. Although Goldwater did not stand for reelection to the Senate that year, he returned to the Senate after winning election in 1968.
1965
A statue of Father Eusebio Francisco Kino, a Jesuit missionary, sculpted by Suzanne Silvercruys, was unveiled in the Capitol as Arizona's second contribution to the National Statuary Hall Collection.
1969
Senator Paul J. Fannin of Phoenix delivered George Washington's Farewell Address to the U.S. Senate, a tradition dating to 1862.
1971
The Senate confirmed the nomination of William H. Rehnquist of Phoenix, as associate justice of the Supreme Court.
1978
The Senate approved the "DeConcini Reservation" to the first of the Panama Canal Treaties. Offered by Senator Dennis DeConcini of Tucson, the provision authorized the use of military force "to reopen the Canal or restore operations to the Canal" if necessary, and helped secure sufficient support to win passage of the treaties.
1981
Barry Goldwater became chairman of the Senate Select Committee on Intelligence, serving until 1985, when he became chairman of the Senate Committee on Armed Services . He chaired that committee until his retirement in 1987.
1981
The Senate confirmed the nomination of Sandra Day O'Connor of Arizona as the first woman associate justice of the Supreme Court.
1986
Senator Barry Goldwater received the Presidential Medal of Freedom, given by the president of the United States to honor individuals who have made great contributions to either the United States or the world. To date, 30 senators have received the award.
1986
The Senate dedicated a portrait bust of former senator Carl Hayden, sculpted by Stafford Rolph. The bronze bust is located in the northwest corner of the Russell Senate Office Building, on the first floor, near the office that Senator Hayden had occupied for more than 20 years.
1986
The Senate confirmed the nomination of Supreme Court Associate Justice William Rehnquist as Chief Justice of the United States.
1986
President Ronald Reagan signed the Goldwater-Nichols Act. Sponsored by Arizona senator Barry Goldwater and Alabama representative William Nichols, the act reorganized the Department of Defense and streamlined the military chain of command.
1987
Senator John S. McCain III of Phoenix delivered George Washington's Farewell Address to the U.S. Senate, a tradition dating to 1862.
1993
Dennis DeConcini became chairman of the Senate Select Committee on Intelligence, serving until 1995.
1995
John S. McCain became chairman of the Senate Committee on Indian Affairs, serving until 1997 and again from 2005 to 2007.
1996
Senator Jon L. Kyl of Phoenix received the Golden Gavel Award for presiding over the Senate for 100 hours in a single session.
1997
John McCain became chairman of the Senate Committee on Commerce, Science, and Transportation, serving until 2001, and again from 2003 to 2005.
1999
Senator John McCain began a book tour in support of Faith of My Fathers, a biography that became a national best seller.
2000
Senator John McCain won the Republican presidential primary in New Hampshire but lost the presidential nomination to George W. Bush later in the year.
2002
Jon L. Kyl of Phoenix was elected chairman of the Senate Republican Policy Committee for the 108th Congress, a position he held until 2007, when he became Republican Conference chairman.
2007
Senate Republicans elected Jon L. Kyl as their party whip to replace Trent Lott, who was resigning, effective December 18, 2007. Kyl served as whip until his retirement on January 3, 2013.
2008
Senator John McCain won the Republican Party's presidential nomination but lost in the November election to Senator Barack Obama.
2015
John McCain became chairman of the Senate Committee on Armed Services, a position he held until his death in August 2018.
2015
A statue of Barry Goldwater was unveiled in the Capitol as part of the National Statuary Hall Collection. Goldwater's statue replaced one of John Greenway that had been unveiled in 1930.
2018
Senator John McCain died of a malignant brain tumor, ending his nearly 32-year Senate career. McCain lay in state in the U.S. Capitol Rotunda on August 31, 2018, the 34th person so honored.
2019
Kyrsten Sinema of Phoenix and Martha McSally of Tucson became the first women to represent Arizona in the U.S. Senate.
2023
Kyrsten Sinema switched her political party affiliation from Democratic to Independent. While she received her seniority and committee assignments through the Democratic Conference for the purposes of organizing the Senate, she indicated she would not participate in either party caucus.
