The Capitol seemed vast—unless you worked there. The building, though grand in scale, had only 56 rooms usable as offices. Most were committee rooms that chairmen could use for themselves. In 1891, the Senate bought an apartment building and converted it to offices. But this structure, the Maltby Building, proved unsound and quickly became obsolete.

By the 20th century, Congress's growing workload made finding more office space essential. Two nearly identical office buildings were constructed, giving every representative and senator a room or two. The buildings also included space for committees and support facilities, such as bathing rooms and telegraph offices. The House Office Building (now the Cannon House Office Building) opened in 1908; the Senate Office Building (now the Russell Senate Office Building) opened the following year.