The 1857 Capitol extension included room for a Members’ post office. Genteel visitors stroll through the grand space, constructed with masonry vaults and fire-proof cast iron trim. The post office remained in this room until 1870, when the Committee on Ways and Means moved into the space.
History, Art & Archives, U.S. House of Representatives, “Members' Post Office, House of Representatives, Washington, DC,” https://history.house.gov/Collection/Listing/2004/2004-086-001/ (June 27, 2022)
Office of the Historian
Office of Art and Archives
Attic, Thomas Jefferson Building
Washington, D.C. 20515