The Coalinga oil district occupies a strip of land about 50 miles in length by 15 miles in width along the northeastern base of the Diablo Range, on the southwest side of the San Joaquin Valley, in western Fresno and Kings counties in central California. The region is accessible by rail from the main lines of both the Southern Pacific and the Atchison, Topeka and Santa Fe railroads by a branch line of the Southern Pacific running westerly from Goshen to Coalinga. The proved productive oil territory is comprised in a band 13 miles long by 3 miles wide in the foothills in the northern end of the district, within the Coalinga field proper, together with a narrow strip along the district's southwestern boundary in the Kreyenhagen field.