Era
19th century
40
20th century
20
Quaternary
4
Revolution, 1775-1783
4
1800-1870
3
Paleozoic
3
1833
2
1838-1883
2
1848
2
1892-1941
2
1942-
2
1960
2
1967
2
1981-
2
Colonial period, ca. 1600-1775
2
1600-1775
1
1723-1792
1
1734-1811
1
1738-1828
1
1756-1843
1
1775-1783
1
1775-1789
1
1780
1
1795
1
1800-1899
1
1810-1891
1
1811
1
1812
1
1822
1
1831
1
1836
1
1841-1919
1
1844-
1
1846
1
1849
1
1858
1
1861 - 1865
1
1861-1865
1
1866-1954
1
1868
1
1872-1929
1
1874
1
1893
1
1895-1958
1
18th century
1
1900 - 1999
1
1900-1910
1
1900-1999
1
1905-
1
1905-1986
1
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