More historic than 8% of U.S. towns · #100 of 140 in Arizona. What drives it
Most of San Luis was built recently: 2% of its homes predate 1940 and the median home dates from 2002. Below: 1 old photo or paper, maps from 1965 on, and the census since 1970.
Founding year: the first San Luis post office (Blevins & Helbock, CC0).The full story ↓
History grade
What drives San Luis’ History grade
On its age, its old homes and the National Register, San Luis is more historic than 8% of U.S. towns, #100 of 140 in Arizona. Its National Register listings hold the grade up; its age pulls it down.
D
HistoryA character grade: shown, never part of San Luis’ overall grade.
Few Arizona towns list much on the Register (a typical Arizona town has 0.1 per 10,000 residents, the U.S. 2.4), so San Luis’ 0.0 sits below most of its state (29% of Arizona towns have fewer) while its 0 listings outnumber those of 23% of U.S. towns.
How sure. Graded on any two of the three inputs instead, the letter would still be D. The pre-1940 share (±1.6 points) is firm at this size. The founding year is the first post office, not a stated founding date.
Founding year: the first post office (other dates in Quick answers). 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 San Luis’ past
Read from the archive, the National Register and the record. The page puts what stands out first.
The city was established in 1930 with the opening of a border-crossing station. In the last twenty years it has registered an accelerated population increase, going from 1,946 inhabitants in 1980, to approximately 20,000 in the year 2005. The city annexed over 16,000 acres (65 km2) of land between 2006 and 2012, thereby increasing the availability of land for residential, commercial and industrial growth in the eastern part of town where the new commercial port of entry will be constructed.
Nothing in the archives for these yearsWeddings on Main Street, storms, parades, school pictures, the old store. If it’s in your family album, it belongs here.
Grew from 189 people in 1970 to 35,257 in 2020, more than tenfold.
6 censuses, 1970–2020.
U.S. Census Bureau decennial counts, from the census table on San Luis’ Wikipedia page.
Places that used to be
Places now gone
San Luis’s post office has been open since 1930.
Gone or out of use
Yuma Number Four Airfieldairport
US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).
Questions about San Luis’ history
What year was San Luis founded?
The San Luis post office opened in 1930, the earliest record of the town by name (U.S. post office records).
How does San Luis rank for history?
San Luis is more historic than 8% of U.S. towns, #100 of 140 in Arizona. 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 San Luis?
2% of San Luis’ homes were built before 1940 (Census estimate, ±1.6 points), against a typical 0.4% for an Arizona town; the median home was built in 2002.
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 (9), Wikipedia, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia), the US Post Offices dataset (Blevins & Helbock) 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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