Altadena is an unincorporated area and census-designated place in Los Angeles County, California, United States, approximately 14 miles (23 km) from the downtown Los Angeles Civic Center, and directly north of the city of Pasadena, California. The population was 42,777 at the 2010 census, up from 42,610 at the 2000 census.
In the mid-1860s, Benjamin Eaton first developed water sources from the Arroyo Seco and Eaton Canyon to irrigate his vineyard near the edge of Eaton Canyon. This made possible the development of Altadena, Pasadena, and South Pasadena. He did the construction for B. D. Wilson and Dr. John Griffin, who jointly owned the Mexican land grant of Rancho San Pascual, about 14,000 acres (57 km2), that was the future sites of these three communities. They hoped to develop and sell this land in a real estate plan called the San Pasqual Plantation. Their efforts failed by 1870, despite Eaton's irrigation ditch that drew water from the site of present-day Jet Propulsion Laboratory in Arroyo Seco, because the land was relatively inaccessible and few believed crops could thrive that close to the mountains.
Eaton tried to sell the land for the partners, and in late 1873 he helped broker a deal with Daniel Berry, who represented a group of investors from Indiana, to buy 4,000 acres (16 km2) of the rancho. This included the land of present-day Altadena, but they developed a 2,500 acres (10 km2) section further south as Pasadena.