The secretary of the Senate and the clerk of the House are responsible for collecting "all the non-current records of the Congress and of each congressional committee and transfer[ring] them to the National Archives for preservation . . ." (42 U.S.C. 2118). The Senate archival collections document floor activities, committee activities, and general Senate administration.
Archives of the United States Senate
Federal Web Harvests capture a one-time snapshot of agency public websites.
The records maintained within a Senator's office are the property of the member. Most Senators donate their papers to a research repository in their home state when they leave office.
The Senate Historical Office maintains a large collection of images that documents the institutional history of the Senate and the careers of Senators.