Columbia subject headings:
Roads--Design and construction--United States--History--19th century.
Roads--Design and construction--United States--History--20th century.
United States. Bureau of Public Roads--History.
Harvard subject headings:
Roads--United States--Design and construction--History--19th century.
Roads--United States--Design and construction--History--20th century.
United States. Bureau of Public Roads--History.
Princeton subject headings:
Roads--Design and construction--United States--History--19th century.
Roads--Design and construction--United States--History--20th century.
United States. Bureau of Public Roads--History.