Columbia subject headings:
Harvard subject headings:
Frontier and pioneer life--West (U.S.)
Pony express
Pony express--History.
West (U.S.)--History--1848-1860.
West (U.S.)--History--1860-1890.
West (U.S.)--History--1890-1945.
Princeton subject headings:
Frontier and pioneer life--West (U.S.)
Indians of North America.
Indians.
Pony express.
West (U.S.)--History--1860-1890.