Era
20th century
23
1929
22
1901-1953
19
Civil War, 1861-1865
18
1933-1945
7
19th century
6
1744-1786
2
1829-1909
2
1898-1951
2
1945-1953
2
1953-1961
2
1961-1969
2
1969-
2
21st century
2
Revolution, 1775-1783
2
1768-1813
1
1783-1865
1
17th century
1
1807-1870
1
1818-1895
1
1847-1882
1
1893-1935
1
18th century
1
1929-1968
1
Colonial period, ca. 1600-1775
1
Indian occupation, 1973
1