"Plan of Principal Story. Design for an Enlargement of the US Capitol, Washington, DC," by Thomas U. Walter, watercolor and ink on paper, 1850

Congress increased in membership as the country expanded during the 1800s, and by mid-century the building had become overcrowded. One possible way of enlarging the Capitol was to build an addition to the principal, or carriage front. This approach had several advantages over the idea of building a pair of wings: the addition could be constructed on level ground and would not entail enlarging the grounds thereby saving money. Philadelphia architect T. U. Walter proposed this scheme for an eastern addition.

Architect of the Capitol