The Senate passed "An act to divide the Indiana territory into two separate governments” (Act of January 11, 1805, ch. 5, 2 Stat. 309). The bill became law on January 11, 1805, with an effective date of June 30, 1805. It designated as the Michigan Territory all the land which “lies north of a line drawn east from the southerly bend or extreme of Lake Michigan, until it shall intersect Lake Erie, and east of a line drawn from said southerly bend through the middle of said lake to its northern extremity, and thence due north to the northern boundary of the United States."
Lewis Cass became governor of the Michigan Territory, serving until 1831. Cass later represented Michigan in the Senate from 1849 to 1857.
Michigan became the 26th state in the Union. Lucius Lyon of Bronson and John Norvell of Detroit presented their credentials and took their oaths of office, becoming Michigan’s first United States senators.
Senators Lyon and Norvell drew lots to determine their class assignments. Senator Lyon drew Class 2, with a term to expire on March 3, 1839. Senator Norvell drew Class 3, with a term to expire on March 3, 1841.
Senator Lewis Cass was the unsuccessful Democratic presidential nominee in the 1848 election. Cass had run in a three-way race against former senator Martin Van Buren and the eventual winner, General Zachary Taylor.
Senator Zachariah Chandler of Detroit became chairman of the Committee on Commerce (today's Committee on Commerce, Science, and Transportation), serving until 1875.
Artist Seth Eastman completed an oil painting of Fort Mackinac, Michigan, part of a series of fort paintings commissioned by House Military Affairs Committee chairman John A. Logan of Illinois. The paintings were originally hung in the House Military Affairs Committee Room, first in the Capitol and later in the Cannon House Office Building. During the late 1930s, they were returned to the Capitol for public display.
Three days after the RMS Titanic sank in the North Atlantic on its maiden voyage, the Senate began its inquiry into the disaster. The subcommittee hearings of the Committee on Commerce (today's Committee on Commerce, Science, and Transportation) were chaired by Michigan senator William Alden Smith.
A marble statue of former senator Zachariah Chandler became Michigan's second contribution to the Capitol's National Statuary Hall Collection. This statue was replaced by one of Gerald R. Ford in 2011.
The Senate condemned Senator Truman Newberry for his excessive campaign expenditures in his election campaign against Henry Ford, the founder of the Ford Motor Company. The election was contested and the Senate called the exorbitant funds spent on the election "harmful to the honor and dignity of the Senate." As a result of the ensuing conflict, Newberry resigned from the Senate later that year.
Senator James Couzens of Detroit became chairman of the Committee on Education and Labor (today's Committee on Health, Education, Labor, and Pensions), serving until 1929. He then became chairman of the Committee on Interstate Commerce, (today's Committee on Commerce, Science, and Transportation), serving until 1933.
Senator Arthur H. Vandenberg was elected the Republican Conference vice chairman. He assumed the chairman position the next day when chairman and floor leader Charles L. McNary of Oregon died. Vandenberg served in this leadership position through 1946.
Senator Arthur H. Vandenberg delivered a rousing and impassioned speech in which he abandoned his typically staunch isolationist point of view and called for global "collective security" as an alternative approach to solidifying global peace following the conclusion of World War II.
The Senate settled the contested election between Representative Frank E. Hook and incumbent senator Homer S. Ferguson of Detroit. Charges of election fraud were investigated and the winner of the election, Senator Ferguson, retained his seat in the Senate.
The Senate voted to name the third Senate office building, which was then under construction, the "Philip A. Hart Senate Office Building" as a tribute to the terminally ill Philip A. Hart of Bryn Mawr. Senator Hart, known as "the Conscience of the Senate," was elected to the Senate in 1959 and served until his death on December 26, 1976.
Carl Levin of Detroit began his senate service. Senator Levin became Michigan's longest-serving senator in January 2002, when he surpassed Senator Arthur H. Vandenberg's previous mark of 23 years and 16 days.
A marble bust of former vice president Gerald Ford was dedicated in a ceremony at the Capitol and added to the Senate Vice Presidential Bust Collection. The bust is on display on the second floor, east corridor of the Senate wing of the Capitol.
Senator Carl Levin became chairman of the Committee on Armed Services after Senator James Jeffords of Vermont changed parties and agreed to caucus with the Democrats. Levin chaired the committee until 2003, and again beginning in 2007.
Debbie A. Stabenow became the first woman to chair the Senate Committee on Agriculture, Nutrition and Forestry.
A bronze statue of former House minority leader, vice president, and president Gerald R. Ford by artist J. Brett Grill was unveiled in the Capitol as Michigan's third contribution to the National Statuary Hall Collection. Ford's statue replaced that of former mayor and U.S. senator Zachariah Chandler.