Era
20th century
179
19th century
60
1945-
21
1933-1945
15
18th century
14
1918-1945
12
17th century
9
1897-1999
8
1945-1989
8
1918-1933
6
Civil War, 1922-1923
5
Colonial period, ca. 1600-1775
5
16th century
4
1878-1953
4
1917-1936
4
Revolution, 1789-1799
4
1887-1940
3
1910-1921
3
1936-1945
3
1936-1953
3
1939-1945
3
1947-
3
1961-1969
3
1964-1979
3
1969-1994
3
Revolution, 1775-1783
3
World War, 1939-1945
3
1564-1616
2
1742-1814
2
1744-1818
2
1846-1919
2
1881-1960
2
1889-1945
2
1910-2001
2
1929
2
1929-1968
2
1945-1955
2
1945-1990
2
1949-1976
2
1953-1985
2
1955-1965
2
1965-1975
2
21st century
2
George III, 1760-1820
2
1599-1647
1
1649-1660
1
1657-1713
1
1711-1799
1
1761-1850
1
1776-1835
1
more ...