Era
20th century
461
1945-
267
19th century
188
1970-
181
1783-1865
101
1865-1918
101
1918-1945
100
Civil War, 1861-1865
79
21st century
76
To 1783
76
1900-1999
69
Since 1900
58
18th century
54
1980-
47
Colonial period, ca. 1600-1775
47
1800-1899
44
1989-
34
2000-2099
30
Since 1970
30
1945-1989
28
Revolution, 1775-1783
25
Since 1945
24
1960-1980
22
1933-1945
20
To 1865
19
17th century
16
1815-1861
16
1861-1865
15
1961-1969
15
1950-
13
1929
12
1945-1970
12
1971-
10
1783-1850
9
1981-1989
9
1700-1799
8
1819-1892
8
1900-2099
8
1945-1953
8
1564-1616
7
1838-1918
7
1865-1898
7
1918-1932
7
1919-1933
7
1969-1974
7
1743-1826
6
1800-1999
6
1805-1859
6
1809-1865
6
1858-1919
6
more ...