Era
20th century
233
19th century
101
21st century
40
1929-1968
15
1951-
15
18th century
12
1865-1950
10
1975-
10
Civil War, 1861-1865
10
To 1964
8
1818-1895
7
1945-
7
To 1863
7
1835-1910
6
1913-2005
6
1945-1989
6
1980-2020
6
1877-1964
5
1897-1962
5
1961-1978
5
Colonial period, ca. 1600-1775
5
1775-1865
4
1863-1877
4
1868-1963
4
1924-1987
4
1925-1965
4
1933-1945
4
1941-1955
4
1946-
4
2008
4
1743-1826
3
1783-1865
3
1789-1869
3
1862-1931
3
1865-1900
3
1865-1933
3
1918-1961
3
1919-1972
3
1964-
3
1965-1979
3
1978-1989
3
1745-1797
2
17th century
2
1800-1859
2
1803-1882
2
1809-1865
2
1811-1896
2
1827-1901
2
1854-1861
2
1861-1886
2
more ...