Classes of United States senators

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The 100 US Senate seats are classified into three classes of United States senators, two of which (class 1 and 2) consist of 33 seats and one (class 3) of 34 seats. The classes determine which Senate seats will be up for election in any two-year cycle, with only one class being up for election, so that elections for class 1 seats took place in 2018, for class 2 in 2020, and the elections for class 3 seats will be held in 2022.

The three classes were established by Article I, Section 3, Clause 2 of the U.S. Constitution. The actual division was originally performed by the Senate in May 1789 by lot, with a proviso that a state's two seats had to be in different classes. ^[1] Whenever a new state subsequently joined the union, its two Senate seats were permanently assigned to two different classes by coin toss, while keeping the three classes as close to the same number as possible. ^[2]

A senator's description as junior or senior senator is not related to their class. Rather, a state's senior U.S. senator is the one with the greater seniority in the Senate, which is mostly based on length of service.

History and constitutional footing

The U. S. Constitution sets the term of senators for a fixed term of six years and staggers their elections into three cycles, so that a third of the Senate was up for election every two years. The objective is to promote stability in the Senate, and encourage senators to deliberate measures over time, rather than risk a rapid turnover of the entire chamber every six years. At the same time, it is provided for more frequent elections as opposed to waiting every six years, to prevent senators from permanently combining for "sinister purposes". ^[1]

The three classes of the Senate are specified by Article I, Section 3 of the U. S. Constitution:

Immediately after they shall be assembled in Consequence of the first Election, they shall be divided as equally as may be into three Classes. The Seats of the Senators of the first Class shall be vacated at the Expiration of the second Year, of the second Class at the Expiration of the fourth Year, and of the third Class at the Expiration of the sixth Year, so that one third may be chosen every second Year.

The allocation took place in May 1789, several weeks after the first Senate assembled. Only 20 senators from 10 states were present; North Carolina and Rhode Island and Providence Plantations had not yet ratified the U.S. Constitution, and New York, because of its late ratification, had not yet selected its senators. ^[3] To decide on how to implement the division into classes, on May 11 the Senate appointed a committee consisting of Senators Ellsworth, Carroll, and Few. ^[4] In accordance with their recommendation, on May 14 the Senate divided the members into three classes: ^[5]

Thursday, May 14, 1789. The committee appointed to consider and report a mode of carrying into effect the provision in the second clause of the third section of the first article of the Constitution, reported:

Whereupon, Resolved, That the Senators be divided into three classes:

• The first to consist of Mr. Langdon, Mr. Johnson, Mr. Morris, Mr. Henry, Mr. Izard, and Mr. Gunn;
• The second of Mr. Wingate, Mr. Strong, Mr. Paterson, Mr. Bassett, Mr. Lee, Mr. Butler, and Mr. Few;
• And the third of Mr. Dalton, Mr. Ellsworth, Mr. Elmer, Mr. Maclay, Mr. Read, Mr. Carroll, and Mr. Grayson.

That three papers of an equal size, numbered 1, 2, and 3, be, by the Secretary, rolled up and put into a box, and drawn by Mr. Langdon, Mr. Wingate, and Mr. Dalton, in behalf of the respective classes in which each of them are placed; and that the classes shall vacate their seats in the Senate according to the order of numbers drawn for them, beginning with number one: And that, when Senators shall take their seats from States that have not yet appointed Senators, they shall be placed by lot in the foregoing classes, but in such manner as shall keep the classes as nearly equal as may be in numbers.

On the next day, May 15, the term expiration of each class was determined by drawing lots. ^[5] Lot 1 was drawn by Dalton, 2 by Wingate, and 3 Langdon.

Upon the expiration of a senator's term of any length, someone starts a new six-year term as senator (based on election by the state legislatures until the Seventeenth Amendment required direct popular election of senators).

Because each state is represented by two senators, regardless of population, each class varies in electorate and populace. Since the early 19th century it so happens Class 2 senators cumulatively co-represent 50–60% of the population; senators from each of the other two classes: 70–75% of the population of the United States. ^[6] (Because each state has two senators, the sum total of these figures is 200%, not 100%.) Relatively populous states California, New York, Florida, Pennsylvania, and Ohio have their senators in classes 1 and 3, provoking this imbalance.

Class 1

Map shows the classes in each U.S. State:

  Classes 1 and 2

  Classes 1 and 3

  Classes 2 and 3

Applies to those States, in the figured map, which are not shaded cyan

Class 1 consists of:

• the 33 current senators whose seats are scheduled for re-election in November 2024, and whose terms end January 3, 2025; and
• earlier senators with terms that ended in 1791, 1797, 1803, 1809, 1815, 1821, 1827, 1833, 1839, 1845, 1851, 1857, 1863, 1869, 1875, 1881, 1887, 1893, 1899, 1905, 1911, 1917, 1923, 1929, 1935, 1941, 1947, 1953, 1959, 1965, 1971, 1977, 1983, 1989, 1995, 2001, 2007, 2013, and 2019.

States with a class 1 senator: Arizona, California, Connecticut, Delaware, Florida, Hawaii, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Dakota, Ohio, Pennsylvania, Rhode Island, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

Class 2

Applies to those States, in the figured map, which are not shaded pink

Class 2 consists of:

• the 33 current senators whose seats are scheduled for re-election in November 2026, and whose terms end January 3, 2027; and
• earlier senators with terms that ended in 1793, 1799, 1805, 1811, 1817, 1823, 1829, 1835, 1841, 1847, 1853, 1859, 1865, 1871, 1877, 1883, 1889, 1895, 1901, 1907, 1913, 1919, 1925, 1931, 1937, 1943, 1949, 1955, 1961, 1967, 1973, 1979, 1985, 1991, 1997, 2003, 2009, 2015, and 2021.

States with a class 2 senator: Alabama, Alaska, Arkansas, Colorado, Delaware, Georgia, Idaho, Illinois, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, North Carolina, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, West Virginia, and Wyoming.

Class 3

Applies to those States, in the figured map, which are not shaded green

Class 3 consists of:

• the 34 current senators whose seats are scheduled for re-election in November 2022, and whose terms end January 3, 2023; and
• earlier senators with terms that ended in 1795, 1801, 1807, 1813, 1819, 1825, 1831, 1837, 1843, 1849, 1855, 1861, 1867, 1873, 1879, 1885, 1891, 1897, 1903, 1909, 1915, 1921, 1927, 1933, 1939, 1945, 1951, 1957, 1963, 1969, 1975, 1981, 1987, 1993, 1999, 2005, 2011, and 2017.

States with a class 3 senator: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Missouri, Nevada, New Hampshire, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Utah, Vermont, Washington, and Wisconsin.

Election cycle years

This table is re-sorted every two years so that the next scheduled election year appears at the top.

Class	Most Recent Election Year	Next Scheduled Election Year
Class 3	2016	2022
Class 1	2018	2024
Class 2	2020	2026

Comparison with other U.S. general elections

Basic rotation of U.S. general elections (fixed-terms only ^[1] )

Year	2020	2021	2022	2023	2024
Type	Presidential	Off-yeara	Midterm	Off-yearb	Presidential
President	Yes	No			Yes
Senate	Class II (33 seats)	No	Class III (34 seats)	No	Class I (33 seats)
House	All 435 seats [2]	No	All 435 seats [3]	No	All 435 seats [2]
Governor	11 states, 2 territories DE, IN, MO, MT, NH, NC, ND, UT, VT, WA, WV, AS, PR	2 states NJ, VA	36 states, DC, & 3 territories [4] AL, AK, AZ, AR, CA, CO, CT, FL, GA, HI, ID, IL, IA, KS, ME, MD, MA, MI, MN, NE, NV, NH, NM, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, VT, WI, WY, DC (Mayor), GU, MP, VI	3 states KY, LA, MS	11 states, 2 territories DE, IN, MO, MT, NH, NC, ND, UT, VT, WA, WV, AS, PR
Lieutenant Governor [5]	5 states, 1 territory DE , MO , NC , VT , WA , AS	1 state VA	10 states [6] AL , AR , CA , GA , ID , NV , OK , RI , TX , VT	2 states LA , MS	5 states, 1 territory DE , MO , NC , VT , WA , AS
Secretary of State	8 states MO, MT, NC, OR, PA, VT, WA, WV	None	26 states AL, AZ, AR, CA, CO, CT, GA, ID, IL, IN, IA, KS, MA, MI, MN, NE, NV, NM, ND, OH, RI, SC, TX, VT, WI, WY	2 states KY, MS	8 states MO, MT, NC, OR, PA, VT, WA, WV
Attorney General	10 states IN, MO, MT, NC, OR, PA, UT, VT, WA, WV	1 state VA	29 states, DC, & 2 territories AL, AZ, AR, CA, CO, CT, FL, GA, ID, IL, IA, KS, MD, MA, MI, MN, NE, NV, NM, NY, ND, OH, OK, RI, SC, TX, VT, WI, WY, DC, GU, MP	2 states KY, MS	10 states IN, MO, MT, NC, OR, PA, UT, VT, WA, WV
State Treasurer [7]	9 states MO, NC, ND, OR, PA, UT, VT, WA, WV	None	23 states AL, AZ, AR, CA, CO, CT, FL (CFO), ID, IL, IN, IA, KS, MA, NE, NV, NM, OH, OK, RI, SC, VT, WI, WY	2 states KY, MS	9 states MO, NC, ND, OR, PA, UT, VT, WA, WV
State Comptroller/Controller	None	None	7 states CA, CT, IL, MD, NV, NY, SC	None	None
State Auditor	9 states MT, NC, ND, PA, UT, VT, WA, WV, GU	None	15 states AL, AR, DE, IN, IA, MA, MN, MO, NE, NM, OH, OK, SD, VT, WY	1 state KY	9 states MT, NC, ND, PA, UT, VT, WA, WV, GU
Superintendent of Public Instruction	4 states MT, NC, ND, WA	1 state WI	8 states AZ, CA, GA, ID, OK, SC, SD (incl. Land), WY	None	4 states MT, NC, ND, WA
Agriculture Commissioner	2 states NC, WV	None	6 states AL, FL, GA, IA, ND, SC	2 states KY, MS	2 states NC, WV
Insurance Commissioner	3 states NC, ND, WA,	None	5 states DE, CA GA, KS, OK,	2 states LA, MS	3 states NC, ND, WA,
Other Commissioners & Elected Officials	1 state NC (Labor)	None	8 states AZ (Mine Inspector), AR (Land), GA (Land), NM (Land), ND (Tax), OK (Labor), OR (Labor), TX (Land)	None	1 state NC (Labor)
State Legislatures [8]	44 states, DC, & 5 territories AK, AZ, AR, CA, CO, CT, DE, FL, GA, HI, ID, IL, IN, IO, KS, KY, ME, MA, MI, MN, MO, MN, NE, NV, NH, NM, NY, NC, ND, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, WA, WV, WI, WY, DC, AS, GU, MP, PR, VI	2 states VA, NJ	46 states, DC, & 4 territories AK, AL, AZ, AR, CA, CO, CT, DE, FL, GA, HI, ID, IL, IN, IO, KS, KY, ME, MA, MD, MI, MN, MO, MN, NE, NV, NH, NM, NY, NC, ND, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, WA, WV, WI, WY, DC, AS, GU, MP, VI	4 states LA, MS, NJ, VA	44 states, DC, & 5 territories AK, AZ, AR, CA, CO, CT, DE, FL, GA, HI, ID, IL, IN, IO, KA, KY, ME, MA, MI, MN, MO, MN, NE, NV, NH, NM, NY, NC, ND, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, WA, WV, WI, WY, DC, AS, GU, MP, PR, VI
State Boards of Education [9]	8 states, DC, & 3 territories AL, CO, KS, MI, NE, OH, TX, UT, DC, GU, MP, VI	None	8 states, DC, & 3 territories AL, CO, KS, MI, NE, OH, TX, UT, DC, GU, MP, VI	None	8 states, DC, & 3 territories AL, CO, KS, MI, NE, OH, TX, UT, DC, GU, MP, VI
Other state, local, and tribal offices	Varies

¹ This table does not include special elections, which may be held to fill political offices that have become vacant between the regularly scheduled elections.

² As well as all six non-voting delegates of the U.S. House.

³ As well as five non-voting delegates of the U.S. House. The Resident Commissioner of Puerto Rico instead serves a four-year term that coincides with the presidential term.

⁴ The Governors of New Hampshire and Vermont are each elected to two-year terms. The other 48 state governors and all five territorial governors serve four-year terms.

⁵ In 26 states and 3 territories the Lieutenant Governor is elected on the same ticket as the Governor: AK, CO, CT, FL, HI, IL, IN, IA, KS, KY, MD, MA, MI, MN, MT, NE, NJ, NM, NY, ND, OH, PA, SC, SD, UT, WI, GU, MP, VI.

⁶ Like the Governor, Vermont's other officials are each elected to two-year terms. All other state officers for all other states listed serve four-year terms.

⁷ In some states, the comptroller or controller has the duties equivalent to a treasurer. There are some states with both positions, so both have been included separately.

⁸ This list does not differentiate chambers of each legislature. Forty-nine state legislatures are bicameral; Nebraska is unicameral. Additionally, Washington, DC, Guam, and the US Virgin Islands are unicameral; the other territories are bicameral. All legislatures have varying terms for their members. Many have two-year terms for the lower house and four-year terms for the upper house. Some have all two-year terms and some all four-year terms. Arkansas has a combination of both two- and four-year terms in the same chamber.

⁹ Most states not listed here have a board appointed by the Governor and legislature. All boards listed here have members that serve four-year staggered terms, except Colorado, which has six-year terms, and Guam, which has two-year terms. Most are elected statewide, some are elected from districts. Louisiana, Ohio, Guam, and the Northern Mariana Islands have additional members who are appointed.

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List of current senators by class

See also: List of current United States senators and 117th United States Congress

The following table lists the senators by party by class.

Class 1 Class 2 Class 3 Total Democratic 21 12 13 46 Republican 10 20 21 51 + VP Independent 2 (caucus with Democrats) 0 0 2 Vacant 0 1 0 1 Last election 2018 2020 2016   Next election 2024 2026 2022   TOTAL 33 33 34 100

Senate composition by Class, State & Party

Class 1

Class 2

Class 3

   Democrat   Independent who caucuses with Democrats
   Republican   Independent who caucuses with Republicans
  Independent  Vacant  Not up for election

The following table lists the senators by state and by class, including the states' Cook Partisan Voting Index ratings, which indicate the party direction in which a state tends to lean and the extent of that lean.

State Class 1 Class 2 Class 3 Cook PVI Alabama — Tommy Tuberville (R) Richard Shelby (R) R+13 Alaska — Dan Sullivan (R) Lisa Murkowski (R) R+9 Arizona Kyrsten Sinema (D) — Mark Kelly (D) R+5 Arkansas — Tom Cotton (R) John Boozman (R) R+15 California Dianne Feinstein (D) — Kamala Harris (D) D+12 Colorado — John Hickenlooper (D) Michael Bennet (D) D+1 Connecticut Chris Murphy (D) — Richard Blumenthal (D) D+6 Delaware Tom Carper (D) Chris Coons (D) — D+6 Florida Rick Scott (R) — Marco Rubio (R) R+2 Georgia — Vacant Kelly Loeffler (R) R+5 Hawaii Mazie Hirono (D) — Brian Schatz (D) D+18 Idaho — Jim Risch (R) Mike Crapo (R) R+19 Illinois — Dick Durbin (D) Tammy Duckworth (D) D+7 Indiana Mike Braun (R) — Todd Young (R) R+9 Iowa — Joni Ernst (R) Chuck Grassley (R) R+3 Kansas — Roger Marshall (R) Jerry Moran (R) R+13 Kentucky — Mitch McConnell (R) Rand Paul (R) R+15 Louisiana — Bill Cassidy (R) John Kennedy (R) R+11 Maine Angus King (I) Susan Collins (R) — D+3 Maryland Ben Cardin (D) — Chris Van Hollen (D) D+12 Massachusetts Elizabeth Warren (D) Ed Markey (D) — D+12 Michigan Debbie Stabenow (D) Gary Peters (D) — D+1 Minnesota Amy Klobuchar (D) Tina Smith (D) — D+1 Mississippi Roger Wicker (R) Cindy Hyde-Smith (R) — R+9 Missouri Josh Hawley (R) — Roy Blunt (R) R+9 Montana Jon Tester (D) Steve Daines (R) — R+11 Nebraska Deb Fischer (R) Ben Sasse (R) — R+14 Nevada Jacky Rosen (D) — Catherine Cortez Masto (D) D+1 New Hampshire — Jeanne Shaheen (D) Maggie Hassan (D) Even New Jersey Bob Menendez (D) Cory Booker (D) — D+7 New Mexico Martin Heinrich (D) Ben Ray Luján (D) — D+3 New York Kirsten Gillibrand (D) — Chuck Schumer (D) D+12 North Carolina — Thom Tillis (R) Richard Burr (R) R+3 North Dakota Kevin Cramer (R) — John Hoeven (R) R+17 Ohio Sherrod Brown (D) — Rob Portman (R) R+3 Oklahoma — Jim Inhofe (R) James Lankford (R) R+20 Oregon — Jeff Merkley (D) Ron Wyden (D) D+5 Pennsylvania Bob Casey Jr. (D) — Pat Toomey (R) Even Rhode Island Sheldon Whitehouse (D) Jack Reed (D) — D+10 South Carolina — Lindsey Graham (R) Tim Scott (R) R+8 South Dakota — Mike Rounds (R) John Thune (R) R+14 Tennessee Marsha Blackburn (R) Bill Hagerty (R) — R+14 Texas Ted Cruz (R) John Cornyn (R) — R+8 Utah Mitt Romney (R) — Mike Lee (R) R+20 Vermont Bernie Sanders (I) — Patrick Leahy (D) D+15 Virginia Tim Kaine (D) Mark Warner (D) — D+1 Washington Maria Cantwell (D) — Patty Murray (D) D+7 West Virginia Joe Manchin (D) Shelley Moore Capito (R) — R+19 Wisconsin Tammy Baldwin (D) — Ron Johnson (R) Even Wyoming John Barrasso (R) Cynthia Lummis (R) — R+25

Addition of new states to the Union

When a new state is admitted to the Union, its two senators have terms that correspond to those of two different classes, among the three classes defined below. Which two classes is determined by a scheme that keeps the three classes as close to the same size as possible; one that avoids the largest class differing by more than one senator from the smallest class. ^[2] A coin toss determines which new senator enters which of the classes selected to be expanded. ^[2]

This means at least one of any new state's first pair of senators has a term of more than two and up to six years, and the other has a term that is either two or four years shorter.

When the last state, Hawaii, was admitted in 1959, candidates for the Senate ran either for "seat A" or "seat B". The new senators, in a process managed by the Secretary of the Senate, drew lots to determine which of the two would join the class 1 (whose term would end in five-and-a-half years), and which would join class 3 (whose term would end in three-and-a-half years). ^{[7] [8]}

Should a 51st state be admitted, it would receive senators in classes 1 and 2, at which point all three classes would have 34 senators. ^[2]

References

1. "The Senate and the United States Constitution". senate.gov. Retrieved October 23, 2011.
2. "Frequently Asked Questions about a New Congress". United States Senate. Retrieved June 11, 2013.
3. "Senators Receive Class Assignments". Senate History. United States Senate. Retrieved January 10, 2015.
4. "Annals of Congress". Constitution Society. Retrieved August 4, 2016.
5. "Journal of the Senate of the United States of America". Journal of the Senate of the United States of America, 1789–1793. Library of Congress. May 14, 1789. Retrieved June 11, 2013.
6. Skelley, Geoffrey (May 29, 2014). "Senate Class Population Imbalance". Sabato's Crystal Ball. Retrieved May 30, 2014.
7. Davies, Lawrence E. (July 30, 1959). "G.O.P. Wins Governorship in Hawaii's First State Vote". The New York Times .
8. Trussell, C. P. (August 25, 1959). "Congress Hails Three New Members from 50th State". The New York Times .

External links

• United States Senate class page (old)
• Current class 1, (senate.gov)
• Current class 2, (senate.gov)
• Current class 3, (senate.gov)
• A 2013 analysis of the partisan leanings of each class