Near this site on July 22, 1760, Captain Gaspar de Portola, joined by 63 men and two priests, crossed the Arroyo Trabuco during the first Spanish expedition into Alta California. On June 8, 1992, the County of Orange, the City of Mission Viejo, Santa Margarita Company, and Rancho Mission Viejo joined together with the opening of Oso Parkway Bridge to recognize the historical significance of the site and its importance as a major crossing for present and future generations.