Era
20th century
3,253
19th century
1,174
Civil War, 1861-1865
919
21st century
893
1945-1989
594
Revolution, 1775-1783
487
1945-
420
1946-
413
2009-
402
2001-2009
389
1933-1945
344
18th century
281
1989-
279
1993-2001
223
1981-2001
217
Colonial period, ca. 1600-1775
178
1945-1953
168
1929
153
1960-
151
1783-1865
148
1953-1961
148
Cretaceous
143
1981-1989
135
1951-
134
1948-
125
1809-1865
124
1882-1945
123
1969-
115
1991-
115
1775-1783
110
1918-1945
110
1960-1980
110
1965-
108
1970-
107
1980-
106
1969-1974
102
1980-2020
101
World War, 1939-1945
101
1913-1994
98
1952-
97
1959-
96
1917-1963
93
1954-
92
1981-1993
92
1865-1918
91
2016
91
To 1775
91
War of 1812
89
1961-
88
1963-1969
87
more ...