Era
20th century
117
1564-1616
32
19th century
32
Colonial period, ca. 1600-1775
23
Civil War, 1861-1865
22
1945-1989
19
18th century
17
Early modern, 1500-1700
16
1809-1865
12
Early church, ca. 30-600
12
To 1775
12
1918-1945
10
Revolution, 1775-1783
10
16th century
9
1789-1900
9
17th century
9
Old English, ca. 450-1100
9
1818-1883
8
1945-
8
1412-1431
7
1783-1865
7
1815-1861
7
1871-1918
7
1933-1945
7
Cretaceous
7
1608-1674
6
1775-1865
6
1819-1891
6
1913-1921
6
1945-1964
6
Revolution, 1789-1799
6
-1400
5
1588-1679
5
1685-1750
5
1743-1826
5
1842-1910
5
1865-1950
5
1955-1965
5
476-1492
5
Ordovician
5
Puritan Revolution, 1642-1660
5
To 70 A.D.
5
1724-1804
4
1812-1870
4
1856-1924
4
1858-1919
4
1861-1865
4
1866-1895
4
1882-1945
4
1889-1945
4
more ...