The highest estimate comes from Sherburne F. Cook, who in later life concluded there were 26,000 Ohlone and Salinans in the "Northern Mission Area". Per Cook, the "Northern Mission Area" means "the region inhabited by the Costanoans and Salinans between San Francisco Bay and the headwaters of the Salinas River. To this may be added for convenience the local area under the jurisdiction of the San Luis Obispo even though there is an infringement of the Chumash." In this model, the Ohlone people's territory was one half of the "Northern Mission Area". It was however known to be more densely populated than the southern Salinan territory, per Cook: "The Costanoan density was nearly 1.8 persons per square mile with the maximum in the Bay region. The Esselen was approximately 1.3, the Salinan must have been still lower." We can estimate that Cook meant about 18,200 Ohlone based on his own statements (70% of "Northern Mission Area"), plus or minus a few thousand margin for error, but he does not give an exact number.