Columbia subject headings:
Frontier and pioneer life--United States--Historiography.
United States--Territorial expansion--Historiography.
West (U.S.)--Historiography.
Harvard subject headings:
Frontier and pioneer life--United States--Historiography
United States--Territorial expansion--Historiography.
West (U.S.)--Historiography.
Princeton subject headings:
Frontier and pioneer life--United States--Historiography.
United States--Territorial expansion--Historiography.
West (U.S.)--Historiography.