Era
20th century
7
1933-1945
4
1815-1861
3
1945-1989
3
1960-
3
19th century
3
1789-1815
2
1861-1865
2
1874-1965
2
1945-1953
2
1648-1789
1
1767-1845
1
1775-1783
1
1783-1789
1
1808-1875
1
1865-1869
1
1865-1877
1
1865-1933
1
1865-1950
1
1870-1940
1
1884-1962
1
1884-1972
1
1908-1957
1
1918-1933
1
1922-1945
1
1945-
1
1949-1976
1
1961-1963
1
1980-
1
1985-1991
1
1989-
1
1989-1993
1
1993-2001
1
2001-2009
1
21st century
1
Civil War, 1861-1865
1
To 146 B.C.
1
To 1775
1