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Yes, I did a quick a dirty transcription of the US Senate data listed as the source and had not yet put in all the in-session changes for all political parties. The US Senate data does not have in-session changes before the WWII Congresses and will need further research.

The GOP did make the gains in the 1898 mid-terms due to the seat changes from the six new States (North Dakota, South Dakota Montana, Washinton, Idaho, Wyoming) 'Class A' Senators who had stood for re-election after only two years in 1892. Add to that the re-election of the 'Class A' Senators in the newly admitted State of Utah in 1896 and you get enough elections happening, along with the Republicans picking up two 'Silver Republican' third-party seats and you get the unusual nine-seat pick-up...

Here is the corrected table with the updates for the changes in the composition of the Senate from WWII onwards...

US Senate
Historical division by party
1789 to Present

Congress	Years_Term	Senate Majority Party	Allotted Number of Senators	Administration	Opposition	Federalist	Democratic- Republican	Whig	Democrat	Republican	Others	Vacant



1st	1789-1791	Administration	26	18	8
2nd	1791-1793	Administration	26/28/30	16	9/11/13							1
3rd	1793-1795	Administration	30	16/16/17	13/14/13							1/0/0
4th	1795-1797	Federalist	30/32			21	11
5th	1797-1799	Federalist	32			22	10
6th	1799-1801	Federalist	32			22	10
7th	1801-1803	Dem-Reps	32/34			15	17					0/2
8th	1803-1805	Dem-Reps	34			9	25
9th	1805-1807	Dem-Reps	34			7	27
10th	1807-1809	Dem-Reps	34			6	28
11th	1809-1811	Dem-Reps	34			7	27
12th	1811-1813	Dem-Reps	34/36			6	30
13th	1814-1815	Dem-Reps	36			8	28
14th	1815-1817	Dem-Reps	36/38			12	26
15th	1817-1819	Dem-Reps	38/40/42			12	30
16th	1819-1821	Dem-Reps	42/44/46			9	37
17th	1821-1823	Dem-Reps	48			4	44
18th	1823-1825	Dem-Reps	48			17	31
19th	1825-1827	Dem-Reps	48			22	26
20th	1827-1829	Dem-Reps	48			21	27
21st	1829-1831	Democrat	48					23	25
22nd	1831-1833	Democrat	48					22	24
23rd	1834-1835	Whigs	48					26	20		2
24th	1835-1837	Democrat	48/50/52					24	26		2
25th	1837-1839	Democrat	52					17	35
26th	1839-1841	Democrat	52					22	30
27th	1841-1843	Whigs	52					29	22			1
28th	1843-1845	Whigs	52					29	23
29th	1845-1847	Democrat	52/54/56/58					22	34			2
30th	1847-1849	Democrat	58/60					21	38		1
31st	1849-1851	Democrat	60/62					25	35		2
32nd	1851-1853	Democrat	62					23	36		3
33rd	1853-1855	Democrat	62					22	38		2
34th	1855-1857	Democrat	62						42	15	5
35th	1857-1859	Democrat	62/64						39	20	5
36th	1859-1861	Democrat	64/66/68						38	26	2
37th	1861-1863	Republican	50						15	31	3	1
38th	1863-1865	Republican	52						10	33	9
39th	1865-1867	Republican	54						11	39	4
40th	1867-1869	Republican	68						9	57		2
41st	1869-1871	Republican	74						12	62
42nd	1871-1873	Republican	74						17	56	1
43rd	1873-1875	Republican	74						19	47	7	1
44th	1875-1877	Republican	76						28	46	1	1
45th	1877-1879	Republican	76						35	40	1
46th	1879-1881	Republican	76						33	42	1
47th	1881-1883	Republican	76						37	37	2
48th	1883-1885	Republican	76						36	38	2
49th	1885-1887	Republican	76						34	42
50th	1887-1889	Republican	76						37	39
51st	1889-1891	Republican	88						37	51
52nd	1891-1893	Republican	88						39	47	2
53rd	1893-1895	Republican	88						40	44	4
54th	1895-1897	Republican	90						40	44	6
55th	1897-1899	Republican	90						34	44	12
56th	1899-1901	Republican	90						26	53	10	1
57th	1901-1903	Republican	90						32	56	2
58th	1903-1905	Republican	90						33	57
59th	1905-1907	Republican	90						32	58
60th	1907-1909	Republican	92						31	61
61st	1909-1911	Republican	92						32	60
62nd	1911-1913	Republican	96						44	52
63rd	1913-1915	Republican	96						44	51		1
64th	1915-1917	Democrat	96						56	40
65th	1917-1919	Democrat	96						54	42
66th	1919-1921	Republican	96						47	49
67th	1921-1923	Republican	96						37	59
68th	1923-1925	Republican	96						42	53	1
69th	1925-1927	Republican	96						41	54	1
70th	1927-1929	Republican	96						46	48	1	1
71st	1929-1931	Republican	96						39	56	1
72nd	1931-1933	Republican	96						47	48	1
73rd	1933-1935	Democrat	96						59	36	1
74th	1935-1937	Democrat	96						69	25	2
75th	1937-1939	Democrat	96						76	16	3
76th	1939-1941	Democrat	96						69	23	3
77th	1941-1943	Democrat	96						66	28	2
78th	1943-1945	Democrat	96						57	38	1
79th	1945-1947	Democrat	96						57	38	1
80th	1947-1949	Democrat	96						51	45
81st	1949-1951	Democrat	96						54	42
82nd	1951-1953	Democrat	96						49	47
83rd	1953-1955	Republican	96						47	48	1
84th	1955-1957	Democrat	96						47/47/48/49	47/47/47/47	2/1/0/0	0/1/0/0
85th	1957-1959	Democrat	96						49	47
86th	1959-1961	Democrat	100						65	35
87th	1961-1963	Democrat	100						64	36
88th	1963-1965	Democrat	100						66	34
89th	1965-1967	Democrat	100						68	32
90th	1967-1969	Democrat	100						64	36
91st	1969-1971	Democrat	100						57	43
92nd	1971-1973	Democrat	100						54	44	2
93rd	1973-1975	Democrat	100						56	42	2
94th	1975-1977	Democrat	100						60	38	2
95th	1977-1979	Democrat	100						61	38	1
96th	1979-1981	Democrat	100						58	41	1
97th	1981-1983	Republican	100						46	53	1
98th	1983-1985	Republican	100						46	54
99th	1985-1987	Republican	100						47	53
100th	1987-1989	Democrat	100						55	45
101st	1989-1991	Democrat	100						55	45
102nd	1991-1993	Democrat	100						56	44
103rd	1993-1995	Democrat	100						57/56	43/44
104th	1995-1997	Republican	100						48/47/46/46/47	52/53/54/53/53		0/0/0/1/0
105th	1997-1999	Republican	100						45	55
106th	1999-2001	Republican	100						45/45/45/46	55/54/55/54		0/1/0/0
107th	2001-2003	Rep/Dem	100						50/50/49/48/48	50/49/49/50/50	0/1/1/1/2	0/0/1/1/0
108th	2003-2005	Republican	100						48	51	1
109th	2005-2007	Republican	100						44	55	1

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