Era
1976
38
Civil War, 1861-1865
33
1990
28
19th century
23
1978
20
1975
18
1977
18
1979
18
1980
18
1996
18
1971-1980
16
20th century
15
1865
14
1995
14
1968
12
1984
12
1809-1865
11
1861
11
1998
11
1985
10
1863
9
1850
8
1997
8
1860
7
1862
7
1864
7
1870
7
1876
7
1989
7
1855
6
1857
6
1981
6
1988
6
2003
6
1830
5
1858
5
1861-1865
5
1864-1922
5
1889
5
1907
5
1918
5
1982
5
1986
5
1993
5
1999
5
1810
4
1820
4
1833
4
1842
4
1854
4
more ...