Era
20th century
216
19th century
108
Quaternary
33
18th century
29
Cretaceous
26
21st century
24
1919-1972
22
To 1500
22
1945-
16
1895-1948
12
1918-2002
12
1931-1995
11
Precambrian
11
1877-1927
10
1925-2015
10
Civil War, 1861-1865
10
Paleozoic
10
1901-1978
9
Holocene
9
Pre-Quaternary
9
Tertiary
9
1728-1779
8
17th century
8
1872-1929
8
1914-1999
8
Eocene
8
Pleistocene
8
16th century
7
1928-1989
7
1951-
7
Mesozoic
7
1810-1891
6
1881-1965
6
1886-1961
6
1890-1950
6
1906-1982
6
1914-1981
6
1942-
6
1943-
6
1960-
6
1966-
6
1971-
6
Cenozoic
6
Ordovician
6
To 146 B.C.
6
1881-1931
5
1887-1953
5
1891-1972
5
1903-1941
5
1930-2010
5
more ...