Era
20th century
51
19th century
40
1900-1999
26
1809-1865
21
To 1775
14
1800-1899
12
18th century
11
17th century
10
1857-1938
9
1945-1989
8
1951-
8
Colonial period, ca. 1600-1775
8
1815-1861
7
1845-1861
7
1811-1884
6
1815-1882
6
1865-1933
6
1899-1975
6
Civil War, 1861-1865
6
1775-1865
5
1778-1868
5
1946-
5
1700-1799
4
1723-1780
4
1743-1826
4
1767-1845
4
1799-1859
4
1843-1926
4
1886-1968
4
1929-1968
4
1933-1945
4
1935-
4
Since 1951
4
1600-1775
3
1609-1676
3
1750-1823
3
1775-1783
3
1785-1848
3
1796-1865
3
1812-1887
3
1812-1890
3
1835-1892
3
1835-1922
3
1865-1929
3
1888-1976
3
1906-1998
3
1942-
3
1944-
3
1960-
3
21st century
3
more ...