Era
20th century
7,347
19th century
3,401
21st century
942
18th century
940
Civil War, 1861-1865
679
1564-1616
652
1945-
652
1945-1989
623
17th century
494
1933-1945
437
Revolution, 1775-1783
405
Cretaceous
378
Colonial period, ca. 1600-1775
337
1989-
294
Early modern, 1500-1700
286
16th century
285
2001-2009
267
1946-
227
Tertiary
224
1993-2001
195
1809-1865
194
1918-1945
187
Precambrian
181
Paleozoic
176
Quaternary
170
1981-2001
168
1960-
160
1951-
158
Cenozoic
144
1608-1674
143
-1400
138
Permian
136
1882-1945
134
Pennsylvanian
126
1917-1963
125
1991-
124
1981-1989
122
1783-1865
121
Mesozoic
120
To 1500
119
To 1775
118
1882-1941
116
1945-1953
116
1812-1870
110
1960-1980
109
Eocene
107
1819-1891
106
1949-
106
1775-1783
105
1897-1962
105
more ...