These Native Americans were dubbed the Gabrieliño Indians (after San Gabriel, the local mission) by early Spanish colonial explorers, but now generally prefer to be called the Tongva.

Duarte's history with Europeans dates back to 1769, when all land in California was claimed by the king of Spain.

Accompanying Portolà was a Franciscan priest from Junípero Serra's order in Mexico, Juan Crespí, who served as the diarist of the expedition.

[5] The mission was a resting point for early California travelers and gathered most of the native Tongva into an agricultural lifestyle.

On May 10, 1841, the governor of Alta California, Juan Bautista Alvarado, granted to former Mexican corporal Andrés Avelino Duarte and his wife nearly 7,000 acres (28 km2) of prime land in the central-northern San Gabriel Valley.

Following the American Conquest of California, the territory was ceded by Mexico to the United States in 1848 at the end of the Mexican–American War.

Corporal Duarte began incurring legal expenses and other debts, which he defrayed by selling portions of his Rancho.

Corporal Duarte finally won a favorable ruling from the Supreme Court for his land grant case in 1878, but by then he had sold the entire Rancho.

English settlers, Americans from the Midwest and Deep South, Latinos who remained from the Rancho days, and Japanese immigrants enabled Duarte to grow into a thriving agricultural community specializing in citrus production.

In 1913, the Jewish Consumptive Relief Association started a tuberculosis sanitarium in the form of a small tent city on 40 acres (16 ha) of land south of Duarte Road.

This later evolved into the world-renowned City of Hope National Medical Center, a recognized leader in fighting cancer and other catastrophic diseases.

After decades as a full-service hospital, Santa Teresita was downgraded to "medical center" in the early 21st century, after financial problems, caused both by administrative missteps as well as the costs of providing medical coverage to the uninsured, forced the hospital to close its emergency room.

In 1957, a dedicated group of community members, fearing annexation by neighboring cities, led a fight for incorporation.

At the same time, a rival group representing an affluent enclave in the foothills started a competing drive for incorporation and broke off to form the separate city of Bradbury.

Still, many ties between the two communities remain in that they both form the Duarte Unified School District; they both share the same post office and the 91008 ZIP code; and they both share combined public services such as the Los Angeles County Sheriff's Department and Los Angeles County Fire Department, and garbage pickup (provided by Burrtec Waste Services).

It consisted of a double-circular seal, with the inner circle containing an adobe arch featuring the Rancho Azusa de Duarte "d" brand (inside the arch is the original date of the Rancho's establishment, 1841) while the outer circle features the year of Duarte's incorporation (1957).

The city of Duarte is geographically isolated from population centers to the east and south due to the San Gabriel River and rock quarry operations in Irwindale and Azusa.

Still, over the past few decades, the city leadership has succeeded in bringing retail development to the western portion of Duarte.

[16] According to the United States Census Bureau, the city has a total area of 6.7 square miles (17 km2), all land.

According to the 2020 United States Census, Duarte had a median household income of $75,083, with 10.2% of the population living below the federal poverty line.

According to the 2010 United States Census, Duarte had a median household income of $62,250, with 13.4% of the population living below the federal poverty line.

The Hayden Child Care Center is a Roman Catholic-affiliated school serving students in preschool and kindergarten.

Duarte also has its own in-house "Department of Public Safety", where its officers (separate from the LASD) are assigned mainly with issuing citations for various violation of the city's Municipal Code, as well as issuance of dog licenses and bicycle permits.