Era
20th century
297
1900-1999
101
19th century
83
Civil War, 1861-1865
66
1897-1962
50
1941-1955
50
1951-
34
1865-1950
21
1800-1899
20
To 1865
17
1861-1865
16
1909-2001
16
1911-1938
15
1925-1963
15
Siege, 1863
13
18th century
10
1933-
10
To 1803
9
1939-1964
8
1943-1964
8
Since 1900
8
Since 1951
8
1916-1990
7
2005
7
1929-1968
6
21st century
6
To 1964
6
1877-1964
5
1891-1934
5
1922-1997
5
1961-1970
5
Eocene
5
From 40 to 55 million years ago
5
1762-1829
4
1800-1999
4
1865-1900
4
1877-1947
4
1900 - 1999
4
1904-1986
4
1922-
4
1924-2007
4
1929
4
Colonial period, ca. 1600-1775
4
Cretaceous
4
To 1899
4
1700-1899
3
1767-1845
3
1775-1865
3
1822-1885
3
1847-1939
3
more ...