Era
Civil War, 1861-1865
250
Revolution, 1775-1783
179
Colonial period, ca. 1600-1775
109
20th century
83
1933-1945
48
19th century
42
1945-
35
1783-1865
34
1865-1898
32
1815-1861
31
1961-1969
31
18th century
30
1919-1933
30
1809-1865
24
War of 1812
22
1783-1815
19
1775-1783
17
Confederation, 1783-1789
16
To 1775
15
1849-1877
14
1865-
14
1865-1921
13
1918-1945
12
1969-
12
1732-1799
11
1882-1945
11
1929
11
1960-1980
11
1861-1865
10
Constitutional period, 1789-1809
10
1783-1809
9
17th century
9
French and Indian War, 1754-1763
9
To 1865
9
1945-1989
8
1735-1826
7
1767-1845
7
1865-1918
7
1953-1961
7
1783-1789
6
1822-1885
6
1901-1909
6
1989-
6
To 1863
6
1865-1877
5
1917-1963
5
1945-1953
5
To 1763 (New France)
5
1743-1826
4
1751-1836
4
more ...