Era
20th century
28
1884-1972
4
1945-1953
4
1985-1991
4
2001-2009
4
1945-
3
1952-1998
3
1957-2011
3
1981-1989
3
19th century
3
Civil War, 1861-1865
3
1893-1974
2
1941-
2
1945-1989
2
1983-
2
Intervention, 1968
2
1863-1877
1
1882-1945
1
1893-1969
1
1913-1994
1
1917-1987
1
1933-1945
1
1936-1953
1
1937-2006
1
1945-1991
1
1951-1955
1
1953-
1
1953-1985
1
1960-2012
1
1970-1991
1
1975-1985
1
1980-1989
1
1989-
1
1991-2003
1
1993-2001
1
21st century
1
Soviet occupation, 1979-1989
1
To 1863
1