On June 29, 2010, the Orange County Board of Supervisors voted to accept a donation of 20,000 acres from the Irvine Company to the County for preservation and guided recreation. Additional acreage was donated in late 2014. The historic Irvine Ranch’s origins date back to the 1830s as a Mexican Land Grant to Don Jose Andres Sepulveda. In 1876, James Irvine bought out his partners on the land. During this time, he successfully fought to secure the ranch from squatters and the Southern Pacific Railroad.
From 1876 to 2010, the historic Irvine Ranch was used for ranching and mining operations, and evidence of this can still be observed. Based on evaluations and the recommendations of the Science Advisory Committee of the National Park Service, the National Park Service Advisory Board, and the National Park Service director, the Secretary of the Interior designated the Irvine Ranch National Natural Landmark in 2006. A similar review led to the designation as a California Natural Landmark on Earth Day 2008 by the California State Parks director.