List of members of the United States Congress by longevity of service

This is a list of United States congresspersons by longevity of service. It includes those Representatives and Senators who have served at least 36 years. It is divided up into several categories.

In cases where there is a tie in time the following criteria will sort people higher:

The 90th Congress was notable because for a period of 10 days (December 24, 1968 – January 3, 1969), it contained within its Senate all 10 of the longest-serving senators in history until January 7, 2013, when Patrick Leahy surpassed Russell B. Long as the 10th longest-serving senator in history. This period stretched from the installation of Ted Stevens of Alaska after his appointment to fill a vacancy to the retirement of Carl Hayden of Arizona early the next year.

The 96th Congress and 97th Congress were the periods in which most people from this list were serving together (all but Hayden, Russell Jr., Warren, Eastland, and Grassley in the former and all but Hayden, Russell Jr., Warren, Eastland, and Magnuson in the latter).

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