Era
20th century
62
19th century
51
1839-1876
32
1866-1895
26
Civil War, 1861-1865
24
1876-1950
18
21st century
13
1921-1930
12
1821-1894
10
1830-1899
9
Revolution, 1775-1783
9
To 1876
9
-1935
8
1817-1879
8
1834-1902
8
1840-1931
8
1842-1907
7
1846-1917
7
1951-
7
1843-1942
6
1867-1932
6
1911-1920
6
1946-
6
1815-1875
5
Cretaceous
5
Tertiary
5
1829-1890
4
1833-1895
4
1848-1860
4
1851-1887
4
1901-
4
1929
4
Jurassic
4
Quaternary
4
-1792
3
1564-1616
3
1749-1832
3
1779-1813
3
1809-1868
3
1813-1890
3
1837-1927
3
1839-1911
3
1840-1904
3
1843-1924
3
1848-
3
1858-1919
3
1869-1934
3
1870-1952
3
1871-1945
3
1889-1925
3
more ...