Era
20th century
42
19th century
23
Civil War, 1861-1865
15
1948-1980
12
Revolution, 1775-1783
11
1979-
9
To 1775
8
1775-1865
7
1959-1990
7
Colonial period, ca. 1600-1775
6
1834-1902
5
1865-1950
5
18th century
5
1933-1945
5
1945-1989
5
1981-1989
5
Revolution, 1959
5
To 1848
5
1815-1861
4
1822-1893
4
Revolution, 1910-1920
4
1783-1865
3
1865-
3
1865-1918
3
1951-
3
1961-
3
1770-1838
2
1774-1809
2
1793-1863
2
1830-1948
2
1844-1915
2
1857-1861
2
1858-1919
2
1876-1950
2
1909-1933
2
1953-1961
2
1954-
2
1971-
2
1979-1990
2
1979-1992
2
2001-2009
2
Invasion, 1961
2
-1792
1
1644-1718
1
1660-1714
1
1706-1790
1
1711-1780
1
1712-1779
1
1726-1785
1
1731-1803
1
more ...