Era
20th century
92
2009-
68
21st century
55
1991-
32
2001-2009
27
Quaternary
27
2001-
24
2003-
22
Cretaceous
20
Civil War, 1861-1865
17
1951-
16
1989-
15
Civil War, 2011-
15
1993-
14
19th century
14
1960-
12
1980-
12
1956-
11
1965-
11
1990-
11
2000-
11
1945-
10
1946-
10
1957-
10
1964-
10
1986-
10
Tertiary
10
1958-
9
1991-2003
9
Revolution, 1775-1783
9
1809-1865
8
1942-
8
1944-
8
1948-
8
1949-
8
1959-
8
1997-
8
Holocene
8
Jurassic
8
Paleozoic
8
1952-
7
1963-
7
1966-
7
1969-
7
1988-
7
1937-2006
6
1954-
6
1961-
6
1971-
6
1972-
6
more ...