Era
Civil War, 1861-1865
38
Colonial period, ca. 1600-1775
35
19th century
20
18th century
11
17th century
10
Paleozoic
10
1743-1826
8
1775-1865
8
Revolution, 1775-1783
8
1807-1870
7
Cambrian
6
Tertiary
6
1775-1783
5
Devonian
5
Pliocene
5
To 1775
5
Triassic
5
1732-1799
4
20th century
4
Mesozoic
4
-1617
3
1781-1857
3
1783-1809
3
Cretaceous
3
Eocene
3
Mississippian
3
Pennsylvanian
3
Pleistocene
3
1580-1631
2
1736-1799
2
1783-1789
2
1783-1865
2
1864-1934
2
1874-1964
2
Cenozoic
2
Holocene
2
Jurassic
2
Miocene
2
Ordovician
2
Precambrian
2
Siege, 1864-1865
2
-1635
1
-1646
1
-2017
1
1533?-1588
1
1554-1610
1
1564-1616
1
1572?-1621
1
1585-1590
1
1595-1623
1
more ...