This is a chronological listing of the United States Senators from Pennsylvania.

United States Senators are popularly elected, for a six-year term, beginning January 3. Elections are held the first Tuesday after November 1st. Before 1914, they were chosen by the Pennsylvania General Assembly, and before 1935, their terms began March 4.

Class 1 Senators

Class 1 U.S. Senators belong to the electoral cycle that were elected for one session of the U.S. Congress in the first election of 1788 and whose seats in recent years are contested in 1994, 2000, 2006, and 2012.

#	Senator		Took office	Left office	Party	Residence	Background	Congress	Term
1	William Maclay		March 4 1789	March 3 1791 (Lost re-election)	Anti-Administration	Dauphin	Lawyer	1	1
Vacant			March 4 1791	December 1 1793				2	2
								3
2	Albert Gallatin		December 2 1793	February 28 1794 (Election voided)	Anti-Administration	Fayette County	Pennsylvania House of Representatives
Vacant			March 1 1794	April 23 1794
3	James Ross		April 24 1794	March 3 1803	Federalist	Pittsburgh	Lawyer
								4
								5	3
								6
								7
4	Samuel Maclay		March 4 1803	January 4 1809	Democratic-Republican	Lewisburg	Pennsylvania Senate	8	4
								9
								10
5	Michael Leib		January 9 1809	February 14 1814	Democratic-Republican	Philadelphia	Pennsylvania House of Representatives
								11	5
								12
								13
6	Jonathan Roberts		February 24 1814	March 3 1821	Democratic-Republican	Norristown	Pennsylvania House of Representatives
								14	6
								15
								16
Vacant			March 4 1821	December 10 1821				17	7
7	William Findlay		December 10 1821	March 3 1827	Democratic-Republican	Franklinton	Governor of Pennsylvania
								18
								19
8	Isaac D. Barnard		March 4 1827	December 6 1831	Jacksonian	West Chester	Secretary of the Commonwealth of Pennsylvania	20	8
								21
9	George Mifflin Dallas		December 13 1831	March 3 1833	Jacksonian	Philadelphia	U.S. Attorney for the Eastern District of Pennsylvania
								22
10	Samuel McKean		March 4 1833	March 3 1839	Jacksonian	Burlington	Pennsylvania Senate	23	9
								24
								25
Vacant			March 4 1839	January 14 1840				26	10
11	Daniel Sturgeon		January 14 1840	March 3 1851	Democratic	Uniontown	Treasurer of Pennsylvania
								27
								28
								29	11
								30
								31
12	Richard Brodhead		March 4 1851	March 3 1857	Democratic	Easton	U.S. Representative (Pa.-10)	32	12
								33
								34
13	Simon Cameron		March 4 1857	March 4 1861	Republican	Harrisburg	U.S. Senator	35	13
								36
								37
14	David Wilmot		March 14 1861	March 3 1863	Republican	Towanda	U.S. Representative (Pa.-12)
15	Charles R. Buckalew		March 4 1863	March 3 1869	Democratic	Bloomsburg	Minister Resident to Ecuador	38	14
								39
								40
16	John Scott		March 4 1869	March 3 1875	Republican	Huntingdon	Lawyer	41	15
								42
								43
17	William A. Wallace		March 4 1875	March 3 1881	Democratic	Clearfield	Pennsylvania Senate	44	16
								45
								46
18	John I. Mitchell		March 4 1881	March 3 1887	Republican	Wellsboro	U.S. Representative (Pa.-16)	47	17
								48
								49
19	Matthew S. Quay		March 4 1887	March 3 1899	Republican	Beaver	Treasurer of Pennsylvania	50	18
								51
								52
								53	19
								54
								55
Vacant			March 4 1899	January 16 1901				56	20
20	Matthew S. Quay		January 16 1901	May 28 1904	Republican	Beaver	U.S. Senator
								57
								58
21	Philander C. Knox		June 10 1904	March 4 1909	Republican	Pittsburgh	U.S. Attorney General
								59	21
								60
								61
22	George T. Oliver		March 17 1909	March 3 1917	Republican	Pittsburgh	Newspaper Publisher
								62	22
								63
								64
23	Philander C. Knox		March 4 1917	October 12 1921	Republican	Pittsburgh	U.S. Secretary of State	65	23
								66
								67
24	William E. Crow		October 24 1921	August 2 1922	Republican	Uniontown	Pennsylvania Senate
25	David A. Reed		August 8 1922	January 3 1935	Republican	Pittsburgh	Lawyer
								68	24
								69
								70
								71	25
								72
								73
26	Joseph F. Guffey		January 3 1935	January 3 1947	Democratic	Pittsburgh	Businessman	74	26
								75
								76
								77	27
								78
								79
27	Edward Martin		January 3 1947	January 3 1959	Republican	Washington	Governor of Pennsylvania	80	28
								81
								82
								83	29
								84
								85
28	Hugh D. Scott, Jr.		January 3 1959	January 3 1977	Republican	Philadelphia	U.S. Representative (Pa.-6)	86	30
								87
								88
								89	31
								90
								91
								92	32
								93
								94
29	H. John Heinz III		January 3 1977	April 4 1991	Republican	Pittsburgh	U.S. Representative (Pa.-18)	95	33
								96
								97
								98	34
								99
								100
								101	35
								102
30	Harris Wofford		May 9 1991	January 3 1995	Democratic	Bryn Mawr	Pennsylvania Secretary of Labor and Industry
								103
31	Richard J. Santorum		January 3 1995	January 3 2007	Republican	Mount Lebanon/Penn Hills	U.S. Representative (Pa.-18)	104	36
								105
								106
								107	37
								108
								109
32	Robert P. Casey, Jr.		January 3 2007	Incumbent	Democratic	Scranton	Treasurer of Pennsylvania	110	38

Class 3 Senators

Class 3 U.S. Senators belong to the electoral cycle that were elected for three sessions of the U.S. Congress in the first election of 1788 and whose seats in recent years are contested in 1998, 2004, and 2010.

#	Senator		Took office	Left office	Party	Residence	Background	Congress	Term
1	Robert Morris		March 4 1789	March 3 1795	Pro-Administration	Philadelphia	Delegate to the Constitutional Convention	1	1
								2
								3
2	William Bingham		March 4 1795	March 3 1801	Federalist	Philadelphia	Pennsylvania Senate	4	2
								5
								6
3	J. Peter G. Muhlenberg		March 4 1801	June 30 1801	Democratic-Republican	Montgomery County	U.S. Representative (Pa.-4)	7	3
4	George Logan		July 13 1801	March 3 1807	Democratic-Republican	Philadelphia	Pennsylvania House of Representatives
								8
								9
5	Andrew Gregg		March 4 1807	March 3 1813	Democratic-Republican	Pennvalley	U.S. Representative (Pa.-5)	10	4
								11
								12
6	Abner Lacock		March 4 1813	March 3 1819	Democratic-Republican	Beaver	U.S. Representative (Pa.-11)	13	5
								14
								15
7	Walter Lowrie		March 4 1819	March 3 1825	Democratic-Republican	Butler	Pennsylvania Senate	16	6
								17
								18
8	William Marks		March 4 1825	March 3 1831	National Republican	Pittsburgh	Pennsylvania Senate	19	7
								20
								21
9	William Wilkins		March 4 1831	June 30 1834	Jacksonian	Pittsburgh	U.S. Representative (Pa.-6)	22	8
								23
10	James Buchanan		December 6 1834	March 5 1845	Democratic	Lancaster	Minister to Russia
								24
								25	9
								26
								27
								28	10
								29
11	Simon Cameron		March 13 1845	March 3 1849	Democratic	Middletown	Businessman
								30
12	James Cooper		March 4 1849	March 3 1855	Whig	Pottsville	Attorney General of Pennsylvania	31	11
								32
								33
Vacant			March 4 1855	January 14 1856				34	12
13	William Bigler		January 14 1856	March 3 1861	Democratic	Philadelphia	Governor of Pennsylvania
								35
								36
14	Edgar Cowan		March 4 1861	March 3 1867	Republican	Greensburg	Lawyer	37	13
								38
								39
15	Simon Cameron		March 4 1867	March 12 1877	Republican	Harrisburg	Minister to Russia	40	14
								41
								42
								43	15
								44
								45
16	J. Donald Cameron		March 20 1877	March 3 1897	Republican	Harrisburg	U.S. Secretary of War
								46	16
								47
								48
								49	17
								50
								51
								52	18
								53
								54
17	Boies Penrose		March 4 1897	December 31 1921	Republican	Philadelphia	Pennsylvania Senate	55	19
								56
								57
								58	20
								59
								60
								61	21
								62
								63
								64	22
								65
								66
								67	23
18	George Wharton Pepper		January 9 1922	March 3 1927	Republican	Philadelphia	Lawyer
								68
								69
19	William S. Vare		March 4 1927	December 6 1929	Republican	Philadelphia	U.S. Representative (Pa.-1)	70	24
								71
20	Joseph R. Grundy		December 11 1929	December 1 1930	Republican	Bristol	Businessman
21	James J. Davis		December 2 1930	January 3 1945	Republican	Pittsburgh	U.S. Secretary of Labor
								72
								73	25
								74
								75
								76	26
								77
								78
22	Francis J. Myers		January 3 1945	January 3 1951	Democratic	Philadelphia	U.S. Representative (Pa.-6)	79	27
								80
								81
23	James H. Duff		January 3 1951	January 3 1957	Republican	Carnegie	Governor of Pennsylvania	82	28
								83
								84
24	Joseph S. Clark		January 3 1957	January 3 1969	Democratic	Philadelphia	Mayor of Philadelphia	85	29
								86
								87
								88	30
								89
								90
25	Richard S. Schweiker		January 3 1969	January 3 1981	Republican	Worcester	U.S. Representative (Pa.-13)	91	31
								92
								93
								94	32
								95
								96
26	Arlen Specter		January 3 1981	Incumbent	Republican	Philadelphia	Lawyer	97	33
								98
								99
								100	34
								101
								102
								103	35
								104
								105
								106	36
								107
								108
								109	37
								110

References

See also

• United States congressional delegations from Pennsylvania