Wikipedia has the following divisions being deactivated since 1991
Armored divisions
2nd Armored Division: 1940–1995
3rd Armored Division: 1941–1945; 1947–1992
49th Armored Division: 1946–1967; 1973–2004
50th Armored Division: 1946–1993
Infantry divisions
5th Infantry Division: 1939–1950; 1951–1953; 1954–1957; 1962–1992
6th Infantry Division: 1939–1942* (6th Motorized Division); 1943–1949; 1950–1956; 1967–1968; 1984–1998. The 6th Infantry Division itself was deactivated in 1994, but the 1st Brigade, 6th Infantry Division remained in the active force under that designation until being reflagged as the 172nd Infantry Brigade in 1998.
7th Infantry Division: 1940–1942* (7th Motorized Division); 1943–1971; 1974–1994; 1999–2006; 2012
8th Infantry Division: 1940–1942* (8th Motorized Division); 1943–1945; 1950–1992
9th Infantry Division: 1940–1962; 1966–1969; 1972–1991. The Division experienced a brief period of inactivation in 1947.
24th Infantry Division (formerly Hawaiian Division): 1941–1970; 1975-1996; 1999–2006
26th Infantry Division: 1941–1945; 1946–1993
47th Infantry Division: 1946–1991
http://en.wikipedia.org/wiki/Divisio...ed_States_Army
I know a few ACRs are gone as well but cannot find an elegant list.