A History of the Presidio (Source – Presidio Trust.gov)

The Presidio has served as a military reservation from its establishment in 1776 as Spain's northern-most outpost of colonial power in the New World. It was one of the longest-garrisoned posts in the country and the oldest installation in the American West. It played a key role in Spain's exploration and settlement of the borderlands, Mexico's subsequent control of the region from Texas to Alta California, and the United States' involvement not only in frontier expansion, but also in all major conflicts since the Mexican-American War of 1846-48.

~ from the National Historic Landmark Designation, June 13, 1962

Early History
Before the arrival of the Europeans, the Ohlone/Costanoan people seasonally occupied villages in what is now the San Francisco peninsula and gathered shellfish along the Presidio's bayshore. Archaeologists have located a shell mound in the Crissy Field area that dates back to A.D. 740. Important archaeological investigations continue in the Presidio to better understand this period. Today, descendants of the Ohlone/Costanoan people live throughout the Bay Area.
Spanish Outpost (1776 to 1821)
From 1776 to 1821, the Presidio was the Spanish empire's northernmost military outpost and guarded California's largest harbor from occupation by other European powers including Russia and Britain. The original European and Mexican colonists were 193 soldiers and their families from Sonora and Sinaloa in northern Mexico. Founded in conjunction with nearby Mission San Francisco de Asis (Mission Dolores), the Presidio was a place where Ohlone peoples encountered European and mixed-race colonists.
After an earthquake in 1812, the Presidio was rebuilt and its adobe quadrangle doubled in size. The Mesa and de Anza rooms of the Presidio Officers’ Club probably date from this rebuilding. Presidio soldiers and their families spent most of their time farming and ranching at this distant outpost.
Mexican Frontier (1822 to 1846)
In 1821, Mexico declared independence from Spain. It took a year for this news to reach Alta California and there was no change in personnel when the Presidio changed from Spanish to Mexican rule, which lasted 24 years. In 1835, General Mariano Vallejo shifted Mexican forces further north to the plaza at Sonoma, and a caretaker was left in charge of the Presidio.
U.S. Army Post (1846 to 1994)
In 1846, during the Mexican-American War that was triggered by a border dispute in Texas, the 7th New York Volunteer Infantry Regiment occupied the crumbling adobes at the Presidio. The U.S. Regular Army took over the post the following year.
This large military base at the Golden Gate developed into the most important Army post on the Pacific Coast. Over time its armaments evolved from smooth bore cannons to modern missiles. This center of a coastal defense system eventually included Alcatraz and Angel Island, and reached as far north as the Marin Headlands and as far south as Fort Funston (all these former military lands were later incorporated into the Golden Gate National Recreation Area (GGNRA)). Eventually, there were five distinct posts at the Presidio, each with its own commander: the Main Post, Fort Point, Letterman Hospital, Fort Winfield Scott, and Crissy Army Air Field. Also on the 1,491-acre reservation were a Coast Guard lifesaving station and a U.S. Public Health Service Hospital.
From 1847 to about 1890, the Presidio defended San Francisco and also participated in the Indian Wars in the West. From the Spanish-American War of 1898 and the conquest of the Philippines to the end of the Vietnam War in 1973, the Presidio was a key link in the projection of American military power into the Pacific Basin and further west onto the mainland of Asia.
At the close of the 19th century, the Army began extensive forestation of the Presidio, turning grassy hills into dark forests that acted as windbreaks and also beautified the post. In 1874, the Presidio became an "open post" with civilian access, except during wartime. In 1888, Hittell's Guide Book to San Francisco noted that "General McDowell, late commanding the Pacific military division of the national army, made fine roads through the Presidio reservation, planted trees, and commenced other improvements, so as to convert it into a public park, which, in time, may rival the Golden Gate Park in its attractions." New concrete fortifications built after the 1890s indirectly preserved native plant communities on the dramatic Pacific bluffs by making them off-limits.
The Presidio offers a window into the changes in American society over almost 150 years. The shift from an originally bachelor society where only officers could marry to a community with families and children, advances in modern medicine and healthcare at Letterman Hospital, the introduction and expansion of the role of women in the military, the racial integration of the armed forces in advance of American society at large, are all integral to the Presidio's and American national history. The Presidio is home to one of the nation's finest collections of fortifications, landscapes, buildings, structures and artifacts related to military history. It also embraces the oldest national cemetery on the West Coast, the final resting place of many Medal of Honor awardees.
Post to Park (1994-present)
In 1972, the Presidio of San Francisco - then an active military installation - was included within the boundaries of the Golden Gate National Recreation Area (GGNRA). On October 1, 1994, the Army base closed and the land was transferred to the National Park Service.
In 1996, Congress created the Presidio Trust, a federal agency charged with preserving the natural, cultural, scenic, and recreational resources of the Presidio, and transferred administration of the park’s interior lands and more than 700 buildings to the Presidio Trust. Today, the Presidio welcomes local, national, and international visitors and is home to a community of residents and diverse organizations.