Era
20th century
39
19th century
26
1961-1963
12
1775-1783
10
1783-1865
10
1945-1989
10
18th century
9
1933-1945
9
To 1775
9
1861-1865
8
1917-1963
8
1969-1974
8
1815-1861
7
1900-1999
7
1936-1953
7
Civil War, 1861-1865
7
1775-1865
6
17th century
6
1809-1865
6
1878-1953
6
1913-1994
6
1917-1936
6
1963-1969
6
1974-1977
6
Colonial period, ca. 1600-1775
6
Revolution, 1775-1783
5
1743-1826
4
1783-1809
4
1908-1973
4
1913-2006
4
1945-1953
4
1945-1990
4
To 1865
4
1735-1826
3
1751-1836
3
1767-1845
3
1837-1901
3
1849-1877
3
1884-1972
3
1918-1933
3
1923-
3
1946-
3
1951-
3
1953-1961
3
1953-1985
3
2009-2017
3
21st century
3
1592-1672
2
1757-1804
2
1758-1831
2
more ...