The State House Caucus Room marks the end of the 18th-century portion of the State House. It was originally divided into two spaces for the storage of records of the Land Office and the General Court, which became the Court of Appeals in the early 19th century. By 1841, the room was home to the Land Office and there was an exterior entrance in the back corner of the room. Following the 1858 expansion of the Old House of Delegates Chamber, the rear half of the room served as the speaker’s private office, while the front was a cloakroom for the delegates.

The room remained under the jurisdiction of the House of Delegates until completion of the 1905 Annex. In 1906 it was renamed the Flag Room and used to display of the state’s Civil War battle flag collection. A Baltimore Sun article from 1907 described the space as having a “great number of flags of priceless historic value,” and noted that other objects, including ceremonial swords, were displayed in other cases. Records suggest that the room was significantly renovated in 1905 in advance of the installation of the flag exhibition. It appears that the brick vaulted ceiling is part of the original 18th century construction, but further research is required to confirm this detail.

By the 1940s the space had been re-named the Bill Room under the jurisdiction of the Department of Legislative Reference, and it became the Maryland State House Visitor Center by the early 1980s. It remained a visitor center/state welcome center until 2008 when custody transferred to the Maryland Senate.

In 2011, this room was redecorated and renamed the State House Caucus Room. It now serves as a space for legislative meetings and the exhibition of the USS Maryland silver service. The room was re-carpeted and decorated with a deep red velvet wall fabric, the color of the Maryland Senate. Custom museum-quality exhibition cases were built to house the silver, and the room was adorned with Maryland landscape paintings and portraits of nineteenth-century governors. The furnishings, including ten pieces on loan from the Maryland Historical Society augment the display of paintings and the silver. The redecoration was overseen by Johnson Berman, a Baltimore architectural and interior design firm, in conjunction with the Maryland Senate, the Maryland State Archives, and the Department of General Services.