Era
Quaternary
10
20th century
6
Civil War, 1861-1865
5
Paleozoic
5
Cretaceous
4
Mesozoic
4
19th century
3
Jurassic
3
Permian
3
Precambrian
3
Revolution, 1775-1783
3
21st century
2
Cenozoic
2
1200-1259
1
1254-1323?
1
1470-1519
1
1728-1801
1
1729-1824
1
1735-1809
1
1781-1870
1
1810-1873
1
1902-1996
1
1944-
1
1946-
1
1949-1976
1
1980-2020
1
1981-2001
1
2000-
1
2002-
1
476-1492
1
Anglo-Saxon period, 449-1066
1
Middle Ages, 600-1500
1
Miocene
1
Pennsylvanian
1
Tertiary
1
To 146 B.C.
1
To 1500
1