Era
Revolution, 1775-1783
11
1900-1999
6
20th century
6
1939-1945
5
Civil War, 1861-1865
4
1760-1789
3
1979-
3
Colonial period, ca. 1600-1775
3
1809-1817
2
1860-1918
2
1914-
2
1931-1939
2
1939-1975
2
1953-1985
2
1973-
2
1975-
2
Since 1931
2
Since 1979
2
1775-1783
1
1783-1850
1
1783-1865
1
1789-1815
1
1809-1865
1
1816
1
1822-1893
1
1823-1897
1
1847
1
1860
1
1861-1865
1
1865-1898
1
1866-1895
1
1874-1952
1
1883
1
18th century
1
1908-1982
1
1917-
1
1918-1945
1
1933-
1
1933-1945
1
1940-1991
1
1942-1945
1
1945-
1
1945-1955
1
1945-1991
1
1949-
1
1969-1974
1
1993-2001
1
19th century
1
Civil War
1
Civil war
1
more ...