Statistical data are presented from a regional geochemical study of the Ajo 1° x 2° quadrangle exclusive of the Papago Indian Reservation, but including the extension of Organ Pipe Cactus National Monument into the Lukeville 1° x 2° quadrangle. Frequency distribution data from the analysis of stream-sediment and heavy-mineral-concentrate samples for 31 elements have broad ranges and for most elements have maxima well above normal. Elemental associations derived from correlation and R-mode factor analysis related to regional lithologic variation and for some associations suggest mineral-resource potential.