congress	year_start	year_end	seats	p1	np1	p2	np2	other	vac	del	res
1	1789	1791	65	Pro-Administration	37	Anti-Administration	28	0	0	0	0
2	1791	1793	69	Pro-Administration	39	Anti-Administration	30	0	0	0	0
3	1793	1795	106	Pro-Administration	51	Anti-Administration	54	1	0	1	0
4	1795	1797	106	Federalists	47	Jeffersonian Republicans	59	0	0	1	0
5	1797	1799	106	Federalists	57	Jeffersonian Republicans	49	0	0	0	0
6	1799	1801	106	Federalists	60	Jeffersonian Republicans	46	0	0	1	0
7	1801	1803	107	Federalists	38	Jeffersonian Republicans	68	0	1	2	0
8	1803	1805	142	Federalists	39	Jeffersonian Republicans	103	0	0	1	0
9	1805	1807	142	Federalists	28	Jeffersonian Republicans	114	0	0	3	0
10	1807	1809	142	Federalists	26	Jeffersonian Republicans	116	0	0	3	0
11	1809	1811	142	Federalists	50	Jeffersonian Republicans	92	0	0	3	0
12	1811	1813	143	Federalists	36	Jeffersonian Republicans	107	0	0	5	0
13	1813	1815	182	Federalists	68	Jeffersonian Republicans	114	0	0	4	0
14	1815	1817	183	Federalists	64	Jeffersonian Republicans	119	0	0	4	0
15	1817	1819	185	Federalists	39	Jeffersonian Republicans	146	0	0	4	0
16	1819	1821	186	Federalists	26	Jeffersonian Republicans	160	0	0	4	0
17	1821	1823	187	Federalists	32	Jeffersonian Republicans	155	0	0	4	0
18	1823	1825	213	Adams-Clay Republicans	72	Jackson Republicans	64	77	0	3	0
19	1825	1827	213	Adams	109	Jacksons	104	0	0	3	0
20	1827	1829	213	Adams	100	Jacksons	113	0	0	3	0
21	1829	1831	213	Anti-Jacksons	72	Jacksons	136	5	0	3	0
22	1831	1833	213	Anti-Jacksons	66	Jacksons	126	21	0	3	0
23	1833	1835	240	Anti-Jacksons	63	Jacksons	143	34	0	3	0
24	1835	1837	242	Anti-Jacksons	75	Jacksons	143	24	0	4	0
25	1837	1839	242	Democrats	128	Whigs	100	14	0	3	0
26	1839	1841	242	Democrats	125	Whigs	109	8	0	3	0
27	1841	1843	242	Democrats	98	Whigs	142	2	0	3	0
28	1843	1845	223	Democrats	147	Whigs	72	4	0	3	0
29	1845	1847	228	Democrats	142	Whigs	79	6	1	2	0
30	1847	1849	230	Democrats	110	Whigs	116	4	0	1	0
31	1849	1851	233	Democrats	113	Whigs	108	11	1	2	0
32	1851	1853	233	Democrats	127	Whigs	85	21	0	4	0
33	1853	1855	234	Democrats	157	Whigs	71	6	0	7	0
34	1855	1857	234	Democrats	83	Oppositions	100	51	0	7	0
35	1857	1859	237	Democrats	132	Republicans	90	15	0	7	0
36	1859	1861	238	Democrats	83	Republicans	116	39	0	5	0
37	1861	1863	183	Democrats	44	Republicans	108	31	0	7	0
38	1863	1865	184	Democrats	72	Republicans	85	27	0	10	0
39	1865	1867	193	Democrats	38	Republicans	136	19	0	9	0
40	1867	1869	226	Democrats	47	Republicans	173	4	2	8	0
41	1869	1871	243	Democrats	67	Republicans	171	5	0	9	0
42	1871	1873	243	Democrats	104	Republicans	136	3	0	10	0
43	1873	1875	292	Democrats	88	Republicans	199	5	0	10	0
44	1875	1877	293	Democrats	182	Republicans	103	8	0	9	0
45	1877	1879	293	Democrats	155	Republicans	136	2	0	8	0
46	1879	1881	293	Democrats	141	Republicans	132	20	0	8	0
47	1881	1883	293	Democrats	128	Republicans	151	14	0	8	0
48	1883	1885	325	Democrats	196	Republicans	117	12	0	8	0
49	1885	1887	325	Democrats	182	Republicans	141	2	0	8	0
50	1887	1889	325	Democrats	167	Republicans	152	6	0	8	0
51	1889	1891	332	Democrats	152	Republicans	179	1	0	9	0
52	1891	1893	332	Democrats	238	Republicans	86	8	0	4	0
53	1893	1895	356	Democrats	218	Republicans	124	14	0	4	0
54	1895	1897	357	Democrats	93	Republicans	254	10	0	4	0
55	1897	1899	357	Democrats	124	Republicans	206	27	0	3	0
56	1899	1901	357	Democrats	161	Republicans	187	9	0	4	0
57	1901	1903	357	Democrats	151	Republicans	200	6	0	4	1
58	1903	1905	386	Democrats	176	Republicans	207	3	0	4	1
59	1905	1907	386	Democrats	135	Republicans	251	0	0	5	1
60	1907	1909	391	Democrats	167	Republicans	223	1	0	5	1
61	1909	1911	391	Democrats	172	Republicans	219	0	0	4	3
62	1911	1913	394	Democrats	230	Republicans	162	2	0	4	3
63	1913	1915	435	Democrats	291	Republicans	134	10	0	2	3
64	1915	1917	435	Democrats	230	Republicans	196	9	0	2	3
65	1917	1919	435	Democrats	214	Republicans	215	6	0	2	3
66	1919	1921	435	Democrats	192	Republicans	240	2	1	2	3
67	1921	1923	435	Democrats	131	Republicans	302	2	0	2	3
68	1923	1925	435	Democrats	207	Republicans	225	3	0	2	3
69	1925	1927	435	Democrats	183	Republicans	247	5	0	2	3
70	1927	1929	435	Democrats	194	Republicans	238	3	0	2	3
71	1929	1931	435	Democrats	164	Republicans	270	1	0	2	3
72	1931	1933	435	Democrats	216	Republicans	218	1	0	2	3
73	1933	1935	435	Democrats	313	Republicans	117	5	0	2	3
74	1935	1937	435	Democrats	322	Republicans	103	10	0	2	3
75	1937	1939	435	Democrats	334	Republicans	88	13	0	2	2
76	1939	1941	435	Democrats	262	Republicans	169	4	0	2	2
77	1941	1943	435	Democrats	267	Republicans	162	6	0	2	2
78	1943	1945	435	Democrats	222	Republicans	209	4	0	2	2
79	1945	1947	435	Democrats	242	Republicans	191	2	0	2	2
80	1947	1949	435	Democrats	188	Republicans	246	1	0	2	1
81	1949	1951	435	Democrats	263	Republicans	171	1	0	2	1
82	1951	1953	435	Democrats	235	Republicans	199	1	0	2	1
83	1953	1955	435	Democrats	213	Republicans	221	1	0	2	1
84	1955	1957	435	Democrats	232	Republicans	203	0	0	2	1
85	1957	1959	435	Democrats	234	Republicans	201	0	0	2	1
86	1959	1961	437	Democrats	283	Republicans	153	1	0	0	1
87	1961	1963	437	Democrats	263	Republicans	174	0	0	0	1
88	1963	1965	435	Democrats	259	Republicans	176	0	0	0	1
89	1965	1967	435	Democrats	295	Republicans	140	0	0	0	1
90	1967	1969	435	Democrats	247	Republicans	187	0	1	0	1
91	1969	1971	435	Democrats	243	Republicans	192	0	0	0	1
92	1971	1973	435	Democrats	255	Republicans	180	0	0	1	1
93	1973	1975	435	Democrats	242	Republicans	192	1	0	3	1
94	1975	1977	435	Democrats	291	Republicans	144	0	0	3	1
95	1977	1979	435	Democrats	292	Republicans	143	0	0	3	1
96	1979	1981	435	Democrats	277	Republicans	158	0	0	3	1
97	1981	1983	435	Democrats	242	Republicans	192	1	0	4	1
98	1983	1985	435	Democrats	269	Republicans	166	0	0	4	1
99	1985	1987	435	Democrats	253	Republicans	182	0	0	4	1
100	1987	1989	435	Democrats	258	Republicans	177	0	0	4	1
101	1989	1991	435	Democrats	260	Republicans	175	0	0	4	1
102	1991	1993	435	Democrats	267	Republicans	167	1	0	4	1
103	1993	1995	435	Democrats	258	Republicans	176	1	0	4	1
104	1995	1997	435	Democrats	204	Republicans	230	1	0	4	1
105	1997	1999	435	Democrats	206	Republicans	228	1	0	4	1
106	1999	2001	435	Democrats	211	Republicans	223	1	0	4	1
107	2001	2003	435	Democrats	212	Republicans	221	2	0	4	1
108	2003	2005	435	Democrats	205	Republicans	229	1	0	4	1
109	2005	2007	435	Democrats	202	Republicans	232	1	0	4	1
110	2007	2009	435	Democrats	233	Republicans	202	0	0	4	1
111	2009	2011	435	Democrats	257	Republicans	178	0	0	5	1
112	2011	2013	435	Democrats	193	Republicans	242	0	0	5	1
113	2013	2015	435	Democrats	201	Republicans	234	0	0	5	1
114	2015	2017	435	Democrats	188	Republicans	247	0	0	5	1
115	2017	2019	435	Democrats	194	Republicans	241	0	0	5	1
116	2019	2021	435	Democrats	235	Republicans	199	0	0	5	1