Columbia subject headings:
Mountrail County (N.D.)--Economic conditions.
Oil fields.
Williams County (N.D.)--Economic conditions.
Harvard subject headings:
Mountrail County (N.D.)--Economic conditions.
Williams County (N.D.)--Economic conditions.
Princeton subject headings:
Mountrail County (N.D.)--Economic conditions.
Williams County (N.D.)--Economic conditions.