Altadena (pronunciation) (“Alta”, Spanish for “Upper”, and “dena” from Pasadena) is an unincorporated area and census-designated place in the Verdugo Mountains region of Los Angeles County, California, 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.

The make known Altadena derives from the Spanish alta, meaning “upper”, and dena from Pasadena; the area is next-door to, but at a sophisticated elevation than, Pasadena.

In the mid-1860s, Benjamin S. Eaton first developed water sources from the Arroyo Seco and Eaton Canyon to irrigate his vineyard near the edge of Eaton Canyon. This made realistic the go forward of Altadena, Pasadena, and South Pasadena. He did the construction for B. D. Wilson and Dr. John Griffin, who jointly owned the Mexican land attain of Rancho San Pascual, about 14,000 acres (5,700 ha), that would be the well ahead sites of these three communities. They hoped to build and sell this estate in a genuine estate wish called the San Pasqual Plantation. Their efforts unsuccessful by 1870, despite Eaton’s irrigation ditch that drew water from the site of present-day Jet Propulsion Laboratory (JPL) in the Arroyo Seco, because the land was relatively inaccessible and few believed crops could be plentiful that near to the mountains.

Eaton tried to sell the house for the partners, and in late 1873 he helped broker a harmony with Daniel Berry, who represented a group of investors from Indiana, to buy 4,000 acres (1,600 ha) of the rancho. This included the land of present-day Altadena, but they developed a 2,500 acres (1,000 ha) section additional south as Pasadena. In 1881, the house that would higher become Altadena was sold to John and Fred Woodbury, brothers who launched the subdivision of Altadena in 1887. The house remained primarily agricultural, though several eastern millionaires built mansions along Mariposa Street, and a small community developed through the 1890s and into the bordering century.