Era
20th century
34
1960-1980
26
1980-2020
21
1933-1945
19
1945-
18
1945-1989
16
1918-1945
15
To 1865
15
1865-1918
14
19th century
13
1961-1969
11
1929
9
18th century
7
1989-
7
1865-1933
6
Revolution, 1775-1783
6
1918-1932
5
1993-2001
5
1783-1865
4
1815-1861
4
1969-
4
2001-2009
4
21st century
4
Civil War, 1861-1865
4
To 1775
4
17th century
3
1813-1897
3
1865-1921
3
1919-1933
3
1963-1969
3
1970-
3
1975-
3
1981-2001
3
1767-1845
2
1775-1783
2
1818-1895
2
1865-1898
2
1945-1970
2
1946-
2
1981-1989
2
Colonial period, ca. 1600-1775
2
1660-1714
1
16th century
1
1706-1790
1
1712-1794
1
1714-1820
1
1732-1799
1
1745-1797
1
1775-1865
1
1789-1815
1
more ...