The McWhorter Papers are a particularly rich resource for researchers investigating the history of Plateau peoples. Among the many topics represented are Indian-government relations in Eastern Washington, the Nez Perce War of 1877, the Yakima Indian War of 1855-1858, regional tribal conflicts, and McWhorter's important relationships with specific individuals, notably Yellow Wolf and the author Mourning Dove.

McWhorter's papers reflect his lifelong interest and involvement in American Indian concerns; he accumulated books, extensive correspondence, research notes, photographs, and other documents. The manuscript material is included in this collection. His books have been separately cataloged as the "McWhorter Collection" in MASC, and his photographs (described below) are in collection number PC 85.