Etymology The name Altadena was coined by Byron O. Clark, who established Altadena Nursery in 1875. The name combines the
Spanish alta, meaning "upper", with
dena, a term he adapted from
Pasadena. The area is adjacent to, but at a higher elevation than, Pasadena.
Early history 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 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 , that would be 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 (JPL) in the
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 of the rancho. This included the land of present-day Altadena, but they developed a section further south as Pasadena. Byron O. Clark established a nursery in the foothills in 1875, which he named "Altadena Nursery", a name he coined from the Spanish
alta meaning "upper" and
dena from Pasadena. Many notable buildings followed in the 1930s, including Eliot Junior High School (1931) and Davies Community Center in
Farnsworth Park (1934).
Later history Redlining policies prevented
African Americans from acquiring land or purchasing property in much of California. While Altadena long refused wholesale
annexation by neighboring
Pasadena, the larger community nibbled at its edges in several small annexations of neighborhoods through the 1940s. Attempted annexation was stopped in 1956 by community campaigns, though it has been resurrected several times since by Pasadena without success. Had the annexation succeeded, Pasadena would be the
108th largest city in the United States. With early-1960s redevelopment in Pasadena, the routing of extensions of the 134 and 210 freeways, and lawsuits over the desegregation of
Pasadena Unified School District, there was white flight and convulsive racial change in Altadena. In 1960, its black population was under four percent; over the next 15 years, half the White population left, and was replaced by people of color, many of whom settled on the west side of town after being displaced by Pasadena's redevelopment and freeway projects. In 1993, the
Kinneloa Fire, begun accidentally on the slopes above
Eaton Canyon, burned dozens of homes in Altadena and neighboring
Kinneloa Mesa as part of a rash of late October wildfires driven by
Santa Ana winds in Southern California. One man died of complications from smoke inhalation and dozens were injured. In 2022, Altadena gained local coverage in Los Angeles as the place of the first land return to the
Tongva since the arrival of Europeans in the
Los Angeles Basin area, after a resident donated her 1-acre property to the
Tongva Taraxat Paxaavxa Conservancy. It was described as marking the first time in nearly 200 years that the Tongva have had land in
Los Angeles County. In 2022, a single lottery ticket was sold to Edwin Castro, which would win a world record US$2.04 billion
Powerball jackpot, announced on November 7, 2022. After a few months of paperwork, on February 14, 2023, Castro publicly accepted the lump sum prize of US$997.6 million.
Eaton Fire (2025) On January 7, 2025, the
Eaton Fire started in Altadena around 6:30 PM local time (
PT) during powerful
Santa Ana Winds. It quickly spread to by January 10, with 19 confirmed fatalities. Over 9,000 structures were damaged or destroyed, including the
Andrew McNally House,
Altadena Community Church, St. Mark's Episcopal Church,
The Bunny Museum, and
Scripps Hall, as well as much of the downtown area. The entirety of Altadena was put under an evacuation order. In the aftermath of the fires, many homeowners struggled with high rebuilding costs and some were forced to sell, while luxury developers and wealthy individuals scrambled to buy lots in cash at competitive prices. Community groups such as
Altadena Not for Sale quickly formed to advocate for the under- and non-insured to protect against land speculators. Following the January 2025 Eaton Fire in Altadena, Powerball jackpot winner Edwin Castro began purchasing several fire-damaged lots in his hometown. Through his company, Castro announced plans to use a portion of his winnings to construct single-family homes for local residents while preserving the community’s architectural character and preventing speculative real-estate development. Castro's involvement in the rebuilding process has been met with both praise and concern from residents, who cite hopes for community recovery alongside worries about affordability and land consolidation. ==Geography==