The original native inhabitants of this area were the Kumeyaay Indians. They lived in this region for 10,000 years, were hunters and gatherers, and were the people who greeted the Spanish explorers when they first sailed into San Diego harbor with the Juan Rodriguez Cabrillo expedition in 1542. Prehistoric archaeological sites have been identified throughout this area. One such site is the Crestridge Ecological Reserve. Midden, with artifacts and milling components including basins and mortars have been found in this area, confirming unmistakable evidence of Indian occupation.

Over 200 years after Cabrillo had claimed the area for Spain, Alta California’s first mission was founded at San Diego in 1769 by Spanish padres to protect and develop Spain’s claim to the territory. It was hoped that California would be colonized with its own native inhabitants who would become Spanish subjects through the establishment of missions.

Between 1769 and 1820, the mission padres began exploring the area for better pastureland and were led to the El Cajon valley which they realized was an ideal location for raising cattle. The padres saw that they could take advantage of the foothills as a natural barrier for straying cattle and as an aid in collecting rainfall for the grasslands on the valley floor. For years the padres grazed their mission cattle herds here. The padres raised barley, corn, and grapes in the valley. In fact, grapes were still being harvested in 1850 from vines planted 50 years prior in El Cajon valley by the padres.

Mexico won its independence from Spain in 1821. The Republic of Mexico, covering much of what is now California and the Southwestern United States, was established in 1824 and the new government secularized mission lands. In 1845, Pio Pico, the last governor of Alta California under Mexican rule, confiscated the lands of Mission San Diego de Alcala in order to sell or lease the land to Mexican settlers. Later, threatened by the encroachment of the American settlers, Governor Pico gave away vast land grants. One of the largest, the 48,799 acre Rancho El Cajon, was given to Maria Antonia Estudillo de Pedrorena (who was from a prominent San Diego “Californio” family) as repayment of a $500 debt owed by the Mexican government to her husband, Miguel. The El Cajon Rancho was marked by thirteen oak posts. Included within its boundaries were El Cajon, Lakeside, Santee, Bostonia, Flinn Springs, Johnstown, Glenview and parts of Grossmont (and presumably the areas of Crest).

In 1848, the war between Mexico and the United States ended and the El Cajon Rancho became part of the United States. The de Pedrorena family spent much of their time trying to save their land from being confiscated by the U.S. Government. After the Mexican American War, the Land Act of 1851 required all landowners to prove that they in fact held legal title to their land. Many Californio families lost their land during this time since they did not understand the new American laws.

 During the American Civil War, the de Pedrorena siblings started selling off pieces of the rancho. In 1868, the de Pedrorena siblings sold most of the rancho to Isaac Lankershim, who paid less than one dollar per acre.

Following the Civil War, sections of the rancho gradually came into the possession of Americans and it was opened for settlement in 1869. The U.S. Government had told people about mission lands on the West Coast. They were told they could claim the land for themselves and migrations of settlers sought homesteads on the public lands of the West. However, the poorly defined boundaries and legal confusion of Pio Pico’s Rancho Cajon land grant to the de Pedrorenas were to be a source of considerable dispute. Part of the issue was based on the fact that the land then belonged to the United States which did not honor Mexican land grants. As a consequence, historical accounts frequently refer to these pioneering homesteaders by the less noble term of ”squatters.” The de Pedrorena heirs were finally able to prove that their family had lived at the rancho and won legal title to the El Cajon Rancho in 1876.