Greater Los Angeles, Calif., holds the world’s largest urban oil fields, including some of the most productive fields in the United States, within one of the world’s richest oil-producing basins. In 1892, what had been a small agricultural village became a boomtown nearly overnight when oil was first discovered by sinking a well with a pick and a shovel. Since then, many more oil discoveries were made and the city grew up alongside the oil industry, embedding it into the urban environment. The total cumulative production from the Los Angeles Basin amounts to more than 9 billion barrels of oil, mostly from multiple, stacked turbiditic sandstone reservoirs of Late Miocene to Early Pliocene age. Today, many active oil wells remain in Los Angeles, located amid a population of more than 13 million people. Storage tanks, refineries, pipelines, active rod pumps and a few oil rigs dot the metropolitan area, often hidden from sight by tall fences and false buildings.
This is the story of a family and the giant oil field discoveries (Torrance, Dominguez, and Wilmington) made during the 1920s and ‘30s in the Rancho San Pedro, now part of Greater Los Angeles. It had been owned by the Dominguez family since the end of the 18th century, when California was a Spanish territory. The Rancho San Pedro (also known as Rancho Dominguez) passed through successive generations of the Dominguez family during the Spanish, Mexican and United States control over California until the early 20th century.
Oil Seeps and Tar in Los Angeles
Oil seeps and tar at the surface were quite common in the Los Angeles Basin. This led to the early oil discoveries at the end of 19th century by simply drilling wells in the vicinity of seepages. Of course, these oil seeps and tar beds had been known by native Americans for thousands of years. In 1542, Juan Rodríguez Cabrillo, a Spanish marine and the first Western explorer of the Los Angeles area, noticed the native people using the naturally occurring tar to waterproof their canoes. Light oil from the seepages was used as a medicine and for cuts and burns. One of the most famous of these seeps is the La Brea Tar Pits (“brea” is the Spanish word for pitch) where tar, oil and bubbles of gas still exude. They are in the heart of what is today the city of Los Angeles. Over the last 50,000 years, this created shallow pools of black, sticky tar where animals and their predators were frequently trapped. The tar helped preserve all the fossil bones in a perfect state. For its stunning Ice Age fossil record, La Brea Tar Pits was selected in October 2022 by the International Union of Geological Sciences as one of the First 100 IUGS Geological Heritage Sites.
First Spanish Expeditions, Missions, and Land Grants
The first Spanish expeditions to California territory during the second half of the 16th century achieved better knowledge for the map of northwest America but found nothing easily exploitable and marketable in a territory far from Spain. This made the area unattractive to the Spanish for the next 200 years. In the late 1700s, the Spanish renewed their interest in California and began to set up Catholic missions, with mostly Franciscan friars and a few colonial settlers and soldiers quartered in “presidios” (Spanish for military forts). This expanded Spain’s empire along the Pacific coast of North America. More than 20 missions were established by the Spaniards along the California coast, from San Diego to San Francisco. Half a dozen “pueblos” (or town) were founded in California to support these missions. One of them was the small “El Pueblo de Nuestra Señora la Reina de Los Angeles de Porciúncula,” or “The Village of Our Lady the Queen of the Angels,” established in 1781 by order of King Carlos III of Spain, today known as Los Angeles, one of the world’s great cities.
The land not occupied by the missions and pueblos was considered property of the Spanish monarchy. Then, to promote settlement of the territory, large land grants, which were later turned into ranchos, were given at low or no cost to colonists and retired soldiers. They were allowed to use the land and to occupy it, dedicating it mostly to cattle and agriculture. Land development from that time on has often followed ranchos boundaries and many of their Spanish names are still in use. Even today many streets and neighborhoods of Los Angeles County maintain the names of these old ranches (i.e., San Pedro, La Brea, Palos Verdes, Los Cerritos) and former owners (Dominguez, Del Amo, etc.).
The Rancho San Pedro is located some 11 miles south of “El Pueblo de Los Angeles.” It was the first Spanish land grant in California. The land was awarded by King Carlos III in March 1784 to Juan Jose Dominguez, a veteran Spanish soldier who came to California in 1769 with the Gaspar de Portola expedition, Father Junipero Serra and other Franciscan friars. The land was granted in gratitude for the many years of service dedicated to the Spanish Crown. The borders of the original Rancho San Pedro land grant were defined by creeks, hills, slopes and marked by trees, rocks, and other landmarks. It encompassed approximately 75,000 acres, located in the South Bay Region, including what is today Torrance, Carson, Redondo Beach, Palos Verdes and the entire Los Angeles harbor. Within a few years, more land concessions were granted along the coast from San Diego to San Francisco.
Mexico Independence and U.S. Control
In 1821, Mexico gained its independence from Spain and California became a Mexican territory. All the families who had received land grants under Spanish rule were required to present proof of land ownership to the Mexican government to keep their land. In 1826, the Mexican government recognized the ownership rights of the Rancho San Pedro by the Dominguez family. Shortly thereafter, legal disputes began between the heirs, which ended in 1841 with the segregation of the Rancho Los Palos Verdes, which was awarded to the Sepulveda family, leaving the Dominguez family with some 48,000 acres.
In May 1846, the U.S. Congress declared war against Mexico. That August, U.S. military forces occupied “El Pueblo de Los Angeles,” but one month later were forced by the locals to evacuate the village and retreat. Over the following months there were armed conflicts between the U.S. forces and the Los Angeles resistance. One of the skirmishes took place in October 1846 in Rancho San Pedro, by then owned by Manuel Dominguez, which ended with the withdrawal of U.S. forces. This is known as the Battle of Rancho Dominguez or the Battle of Dominguez Hills.
The U.S.-Mexican War formally concluded in February 1848 and California became a part of the United States. After years of political turmoil in California, bitter struggles, prolonged court battles over possession of the Rancho, numerous surveys of the land and the sale of several parcels, in 1858 the U.S. General Land Office accepted the Rancho San Pedro ownership by the Dominguez family.
Rancho San Pedro Partition in 1885
Upon Manuel Dominguez’s death in 1882 and the passing of his wife one year later, the Rancho San Pedro lands, by then comprising a total of 24,000 acres after several land transactions, were partitioned among their six surviving daughters. The partition went into effect in 1885, dividing the Rancho according to a complicated scheme, in such a way that the acreage allotted to each sister had the same value according to the quality, accessibility, location and relative value of the land, but leaving some of the property in undivided ownership.
In 1890, Susana Dominguez, the fifth daughter of Manuel Dominguez, married Gregorio del Amo, a Spanish physician and surgeon born in 1858 in Santoña, a coastal village then in the province of Santander in northern Spain. Once he graduated in 1879, Del Amo emigrated to Montevideo, Uruguay where he practiced medicine, then to Mexico City in 1881. He arrived in Los Angeles in 1882, where he continued his medical practice. It was through his profession that he met the Dominguez family and married Susana. Del Amo was destined to have a powerful influence on the later history of the Dominguez family and the development of the remaining lands of the Rancho San Pedro. While practicing medicine, Del Amo started to manage his wife’s lands. He became the first full-time consul for Spain at San Francisco in 1906, the year of the famous earthquake.
At the beginning of the 20th century, the Dominguez sisters started to form family companies to administer their estates, mostly dedicated to agricultural and grazing activities. The Dominguez Estate Company was created in 1910 as a family corporation to manage the common interests of the sisters in the Rancho San Pedro. Other companies were formed to separately administer holdings, such as the Watson Land Company in 1910, the Carson Estate Company in 1912, the Francis Land Company in 1923 and the Del Amo Estate Company in 1926, all named after four sisters’ spouses’ surnames.
Oil Leases in Rancho San Pedro
Following the oil discoveries in the Los Angeles area during the late 1890s and early 1900s, and the increased oil demand after the first World War, oil companies rushed to acquire leases farther south, in the South Bay region. Gregorio del Amo became devoted full-time to the supervision of his wife’s interest in the Rancho San Pedro land. He signed the first oil lease for the Rancho in February 1920 with the Chanslor-Canfield Midway Oil Co., founded in 1899 by Joseph A. Chanslor and Charles A. Canfield to develop oil wells in the Midway field in the San Joaquin Valley, Calif.
The first oil well on Rancho San Pedro was located on the Del Amo-Dominguez property in the Torrance area at the southwestern side of Rancho San Pedro. The C.C.M.O. Company drilled the Del Amo No. 1 on a long, low-relief hill suggesting an anticlinal closure. The well reached a total depth of 3,500 feet in June 1922, discovering the Torrance oil field, at times known also as Del Amo oil field. The well came in at a rate of 2,500 barrels of oil per day from Pliocene sandstones. Shortly after, a belt of wooden oil derricks carpeted the area, and the field was immediately put on production. By the end of 1922, the field had produced almost 200,000 barrels of 12 to 20 degrees API oil, which provided a remarkable source of income for the Del Amo-Dominguez family. In 1938, a new Miocene oil horizon (named the Del Amo zone) was completed by C.C.M.O. At its peak, the Torrance field had more than 1,500 producing wells. Wooden derricks in the back yards of houses were not uncommon. The field has produced over 230 million barrels of oil and supplied a handsome income for the Dominguez heirs. This oil discovery marked the beginning of widespread activity from Torrance eastward to Dominguez Hills.
The value of the Rancho San Pedro land skyrocketed after the oil discovery on the property of the Dominguez family. They signed additional highly profitable leases with Union Oil Co. of California, Standard Oil Co., Fullerton Oil, General Petroleum Corporation of California, Shell Oil Co. of California, Texas Oil Co., Marland Oil Co. of California, Petroleum Development Co. and many other oil companies.
The year 1923 marked the oil discovery at Dominguez Hills on the northwest side of Rancho San Pedro, site of the famous battle in 1846 during the U.S.-Mexican War and where the Dominguez family home had been built with adobe bricks, perched atop the hill. The Dominguez Hills is a topographic prominence that suggested to geologists an anticline located along the prolific northwest-southeast structural trend of the Newport-Inglewood oil fields. Early drilling in the Dominguez Hills resulted in three unsuccessful wells, which kept the area inactive until September 1923, when the Callender No. 1A well was drilled jointly by the Union Oil Company of California, later known as Unocal, and the Burnham Exploration Company. The latter was co-owned by Major Frederick R. Burnham, a world-traveling adventurer who helped inspire the founding of the international Scout Movement. The Callender No. 1A reached a TD of 4,068 feet and tested 1,500 barrels of oil per day of 31 degrees API oil from Late Miocene to Early Pliocene sandstones. More than 150 wells were soon producing a total of 37,000 barrels a day. Further drilling and testing revealed eight producing levels, designated as Callender zones, and confirmed the Dominguez oil field to be an anticline with northeast-southwest high-angle faults partitioning the field into four major structural blocks with different oil-water contacts, slightly different oil gravities and pressures.
The Dominguez oil field was developed by Union Oil and the other two companies that controlled the productive acreage: Shell Oil Co. and the Dominguez Oil Fields Co. Subsequent to a gas injection process in the late 1920s, Dominguez Field was thought to have the greatest recovery of oil and the least waste of gas. By 1954, a full-scale water flood was implemented to enhance oil recovery. More than 500 wells have been drilled on Dominguez Hills, which has recovered 274 million barrels of oil. In October 1926, the Dominguez family sold 332 acres to Shell Oil to build an oil refinery close to the Dominguez Hills. The sale brought the Dominguez family $7 million in cash. After restoring some of the land, the Dominguez field area became the site of California State University, Dominguez Hills in the 1960s.
The discovery of Wilmington oil field, which partially extends over the southeastern end of Rancho San Pedro, occurred as a result of southeastward (down plunge) development drilling at Torrance field. Wilmington produced oil from the Lower Pliocene as early as 1932 but was not recognized as a giant oil field until 1936 when General Petroleum Corporation of California (later Mobil Oil) drilled the Terminal No. 1 well in the Los Angeles harbor area. The well was completed in the Upper Miocene turbidite sandstones at a depth of 3,625 feet, testing 1,350 barrels of oil per day of 20.5 degrees API oil, thereby establishing a new pay zone. The well proved up three zones that had not been tapped before, showing Wilmington was much larger than previously indicated. Later development was very rapid, leading to the drilling of nearly 2,000 wells in six years. The Wilmington oil field is on trend with the Torrance-Del Amo field, which jointly make a prolific northwest-southeast lineament more than 20 miles long. Wilmington has produced about 3 billion barrels since oil was first discovered by the Del Amo No. 1 well in 1922, and the Torrance-Wilmington-Belmont trend is the largest oil field complex in California.
Del Amo Estate Company and Del Amo Foundation
The Del Amo Estate Co. was established in 1926 under the ownership of Gregorio del Amo and his wife Susana Dominguez. The objective was to manage the operations associated with the Rancho San Pedro properties of the Del Amo-Dominguez family while also giving them the means and time to pursue their philanthropic interests.
When Del Amo passed away in 1941, the company adopted a new business strategy. Leasing and drilling oil wells gradually became less important to the company and came to an end in the early 1950s. Leasing of land to farmers and cattle ranchers continued, but the Del Amo successors saw better opportunities in other industrial activities, like the creation of shopping centers and in the sale of building lots. After the second World War, this formerly rural property became highly desirable for offices, business and housing.
The Del Amo Foundation was established by Gregorio del Amo in May 1929, two years before Susana Dominguez’s death. It was dedicated to managing the considerable business profits to support cultural activities and philanthropic projects, such as an exchange between Spain and California through grants and fellowships to graduate students, scientific researchers and institutions.
Many examples of the businesses and charitable work of the Domínguez and Del Amo family remain in the Los Angeles area, such as the Domínguez Memorial Seminary built for the Claretian Order of the Catholic Church; Del Amo Shopping Center in Torrance (at one time the largest shopping mall in the world); and the Dominguez Rancho Adobe Museum, a California Historical Landmark. But they also left their mark in Madrid, Spain, the city where Gregorio del Amo had graduated in medicine in 1879, by donating $400,000 in 1929 for the construction of an international residence hall named Fundación del Amo, one of the first buildings raised on the new campus of the University City in Madrid. The Del Amo Foundation also provided $500,000 to scholarships for American and Spanish students and professors, especially for medical research, some of whom achieved international prestige.
The residence hall in Madrid was inaugurated in 1930, providing housing for more than 200 international and Spanish graduate students. Unfortunately, the building had a very short history, being nearly destroyed in the siege of Madrid during the Spanish Civil War (1936-39). A second student residence financed by Del Amo Foundation was built in 1967. The residence was named after Jaime del Amo, the adopted Spanish son of the Del Amo-Dominguez marriage, who died in 1966 before the building’s completion. This new residence is located on Gregorio del Amo Avenue of the University Complutense of Madrid and houses students, as well as multiple cultural and sporting activities.
The Del Amo Estate Company was completely liquidated in 1964 by selling all land properties. The Del Amo Foundation continued to function until it was officially dissolved in 1979, 50 years after its creation. The proceeds were donated 50 percent to University Complutense of Madrid, 25 percent to the University of California, Los Angeles, and 25 percent to the University of Southern California. These universities manage the Del Amo legacy to support professional exchanges between Spain and the United States, allowing researchers to conduct their scientific investigations and other academic activities. The Del Amo Foundation archives were transferred to the library of the California State University, Dominguez Hills, located on the land where the Dominguez oil field once stood.
The Dominguez family members kept much of the original Rancho San Pedro land for two centuries, passing from the rule of Spain to Mexico and finally to the United States. The patronage and philanthropy of Gregorio del Amo and Susana Domínguez from the wealth obtained mainly from the oil business has left an important legacy in both California and Spain.
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