A differential density soft sanitary tissue paper web having from about 2% to about 56.5% by weight of the differential density soft sanitary tissue paper web of a softwood pulp fiber mixture, and from about 43.5% to about 99.9% by weight of the dry fiber basis of the differential density soft sanitary tissue paper web of a hardwood pulp fiber mixture is provided. The softwood pulp fiber mixture has: 1) from about 0% to about 56.4% by weight of the dry fiber basis of softwood pulp fiber; 2) from about 0.05% to about 3.0% by weight of the dry fiber basis of strengthening additive. The hardwood pulp fiber mixture comprises: 1) from about 43.4% to about 99.4% by weight of the dry fiber basis of hardwood pulp fibers; and, 2) from about 0.05% to about 20.0% by weight of the dry fiber basis of cellulose nano-filaments.