Era
20th century
28
19th century
19
1876-1950
9
Civil War, 1861-1865
9
-1935
5
1830-1899
5
1839-1876
5
21st century
5
1817-1879
4
1821-1894
4
1866-1895
4
Cretaceous
4
1843-1942
3
1846-1917
3
1867-1932
3
1870-1952
3
To 1876
3
-1792
2
1510-1554
2
1794-1860
2
1812-1901
2
1815-1875
2
1829-1887
2
1833-1895
2
1834-1902
2
1840-1931
2
1848-1860
2
1848-1929
2
1851-1887
2
1860-1890
2
1905-1976
2
1956-
2
1963-
2
2001-2009
2
Mesozoic
2
Revolution, 1775-1783
2
active 1776
2
-1853
1
-1904
1
-1919
1
-1937
1
1564-1616
1
1599-1660
1
1600-1681
1
1601-1658
1
1648-1715
1
1735-1788
1
1739-1824
1
1770-1838
1
1774-1809
1
more ...