Era
20th century
1,664
19th century
808
1900-1999
530
21st century
364
1981-
276
1900 - 1999
256
1914-1918
189
Since 1981
181
1800-1899
174
Civil War, 1861-1865
174
1939-1945
173
20e siècle
144
18th century
135
Early works to 1800
135
1951-
114
Cretaceous
112
1861-1865
103
Quaternary
94
1971-
86
Paleozoic
84
Medieval, 500-1500
83
Geschichte
80
1800-1999
77
2000-2099
75
17th century
73
1976-
73
1945-
66
16th century
63
Revolution, 1775-1783
59
Since 1971
59
Since 1951
58
Pennsylvanian
56
Precambrian
54
1900-2099
53
1800 - 1999
50
Since 1976
50
Tertiary
50
Modern period, 1500-
49
Pleistocene
48
1800 - 1899
46
1975-
46
1951-1980
41
Cenozoic
41
Mesozoic
41
19e siècle
40
From 2 million years ago
39
Permian
38
Devonian
37
Ordovician
37
To 1500
34
more ...