Attention is directed to the petroleum possibilities of the great province that lies between Hudson Bay and the Canadian Rockies. A general review of the sedimentation and earth's movements within this geosyncline of 300,000 square miles, from Cambrian time to the present, indicates that the major features compare favorably with other geosynclines which have yielded large amounts of petroleum. Geologists have already outlined, in a general way, some of the probable petroleum areas, and development has centered about ten localities. The results so far obtained, together with the general favorable conditions and numerous oil seepages, constitute evidence which cannot be ignored by oil companies desiring new producing territory. Systematic geological work has but scarcely be un in the Canadian Great Plains, which are believed to comprise the largest remaining undeveloped area having oil possibilities on the North American continent. A thorough systematic exploration of the region is merited.