More historic than 9% of U.S. towns · #705 of 847 in California. What drives it
Most of Rossmoor was built recently: 0.6% of its homes predate 1940 and the median home dates from 1958. Below: maps from 1896 on and the census since 1970.
On its age, its old homes and the National Register, Rossmoor is more historic than 9% of U.S. towns, #705 of 847 in California. Its National Register listings hold the grade up; its share of homes from before 1940 pulls it down.
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HistoryA character grade: shown, never part of Rossmoor’s overall grade.
Few California towns list much on the Register (a typical California town has 0.0 per 10,000 residents, the U.S. 2.4), so Rossmoor’s 0.0 sits below most of its state (31% of California towns have fewer) while its 0 listings outnumber those of 23% of U.S. towns.
How sure. Graded on two of the three inputs, so a change in either one moves the letter more than it would with three. The pre-1940 share (±0.6 points) is firm at this size.
Founding year: our sources. Homes: Census ACS 2020–24. National Register: National Park Service, May 2026 list; each listing counted once (boundary changes and added documentation belong to their listing), and a historic district counts its contributing buildings. How TownRatings grades history →
What stands out about Rossmoor’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
The Rossmoor community was developed from 1955 through 1961 by Ross W. Cortese, who had earlier developed the architecturally-significant Lakewood Rancho Estates in Long Beach (1953) and the Frematic Homes (1954) in Anaheim, just north and west of Disneyland. Cortese filed his first subdivision map for Rossmoor on October 20, 1956, and filed his thirteenth and final map on March 21, 1960. Cortese's original partners in securing the first large parcels of land that would become Rossmoor included California governor Goodwin Knight and Judge Alfred Gittelson, who had also partnered with him in the Lakewood Rancho Estates and the Frematic homes. (It was Gittelson who later agreed to annex his Rossmoor Shopping Center property to Seal Beach in the late 1960s.) After Rossmoor, Cortese would construct the first of his very successful Leisure World gated retirement communities in that part of …
Rossmoor is more historic than 9% of U.S. towns, #705 of 847 in California. The History grade combines the town’s founding era, the share of homes built before 1940 and its National Register listings. It’s a character grade, so it isn’t part of the overall grade. How it works.
How old are the homes in Rossmoor?
0.6% of Rossmoor’s homes were built before 1940 (Census estimate), against a typical 3.4% for a California town; the median home was built in 1958.
Founding dates: Wikidata, Wikipedia, the U.S. post office records of Blevins & Helbock (CC0) and the Census. Homes by year built: Census ACS 2020–24. National Register of Historic Places: National Park Service (list of May 22, 2026). Old photos, postcards and papers: Wikimedia Commons, the Library of Congress and other public archives, credited on each item’s page. Maps: U.S. Geological Survey historical topographic maps (via Esri) and Sanborn fire-insurance maps (Library of Congress). History text and census tables: Wikipedia (CC BY-SA 4.0). Places that used to be: USGS Geographic Names Information System (2021).
From Wikimedia Commons (2), Wikipedia, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia) and the USGS Geographic Names Information System. Archive images are copied here with their credits and licenses, shown on each photo’s page. Refreshed monthly.
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