Era
19th century
140
20th century
66
1862-1956
11
18th century
11
1900-1999
10
Civil War, 1861-1865
10
To 1800
10
1863
9
Revolution, 1775-1783
9
Devonian
7
1800-1899
6
1884-1954
6
Early works to 1800
6
1700-1799
5
1900 - 1999
5
1981-
5
21st century
5
From 310 to 345 million years ago
5
Mississippian
5
Silurian
5
1775-1783
4
1837-1899
4
2000-2099
4
From 345 to 405 million years ago
4
Pre-Quaternary
4
1800 - 1899
3
1861-1865
3
1872
3
1883-1954
3
1926-2012
3
1933-2014
3
Cambrian
3
Colonial period, ca. 1600-1775
3
From 405 to 425 million years ago
3
Ordovician
3
Since 1981
3
1600-1775
2
1700 - 1899
2
1728-1779
2
1741-1779
2
1750-1831
2
1775 - 1783
2
1777
2
1799-1851
2
1820-1857
2
1840
2
1849
2
1865
2
1870-1945
2
1875
2
more ...