List of United States Secretaries of Defense by time in office

2,595 days Robert McNamara from 1961 to 1968

114 days Elliot Richardson in 1973

This is a list of United States Secretaries of Defense by time in office. This is based on the difference between dates; if counted by number of calendar days all the figures would be one greater. (Note that the list of popes by length of reign uses numbers of calendar days.)

Robert McNamara and Donald Rumsfeld are the only two people to have served as Secretary of Defense for more than 7 years. Rumsfeld is the only Secretary of Defense to have served two non-consecutive terms. Elliot Richardson served as Secretary of Defense for less than four months before becoming Attorney General.

# in office	Secretary	Days	Rank
8	Robert McNamara	2,595	1
13/21	Donald Rumsfeld	2,585	2
15	Caspar Weinberger	2,497	3
5	Charles Erwin Wilson	1,722	4
22	Robert Gates	1,656	5
10	Melvin R. Laird	1,469	6
14	Harold Brown	1,460	7
20	William Cohen	1,457	8
17	Dick Cheney	1,402	9
19	William Perry	1,085	10
12	James R. Schlesinger	870	11
6	Neil H. McElroy	783	12
24	Chuck Hagel	720	13
23	Leon Panetta	608	14
1	James Forrestal	558	15
2	Louis A. Johnson	540	16
4	Robert A. Lovett	491	17
16	Frank Carlucci	424	18
7	Thomas S. Gates, Jr.	415	19
18	Les Aspin	378	20
3	George Marshall	356	21
25	Ashton Carter		22
9	Clark M. Clifford	326	23
11	Elliot Richardson	114	24

See also

• List of United States Chairmen of the Joint Chiefs of Staff by time in office
• List of United States Secretaries of State by time in office