List of members of the United States Congress by longevity of service
This list of members of the United States Congress by longevity of service includes representatives and senators who have served for at least 36 years, in the House, the Senate, or both combined. In cases where there is a tie in time, the following criteria will sort people higher: Senate time. The 90th Congress was notable because for a period of 10 days (December 24, 1968 – January 3, 1969), it contained within the Senate, all 10 of what was at one point the top 10 longest-serving senators  in history (Byrd, Inouye, Thurmond, Kennedy, Hayden, Stennis, Stevens, Hollings, Russell Jr., and Long) until January 7, 2013, when Patrick Leahy surpassed Russell B. Long as the 10th longest-serving senator in history. This period stretched from the appointment of Ted Stevens of Alaska to fill a vacancy to the retirement of Carl Hayden of Arizona early the next year. The 99th Congress (1985–1987) was the period in which most people from this list were serving together (all but Hayden, Russell Jr., Warren, Eastland, and Magnuson).