Founding year: the first Rio post office (Blevins & Helbock, CC0).The full story ↓
History grade
What drives Rio’s History grade
On its age, its old homes and the National Register, Rio is more historic than 28% of U.S. towns. Its share of homes from before 1940 holds the grade up; its National Register listings pull it down.
C
HistoryA character grade: shown, never part of Rio’s overall grade.
Few Florida towns list much on the Register (a typical Florida town has 0.0 per 10,000 residents, the U.S. 2.4), so Rio’s 0.0 sits below most of its state (33% of Florida 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 C. The pre-1940 share is a Census survey estimate (±11.7 points). 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 Rio’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Rio proper was platted as "Rio St. Lucie", but the post office established on March 24, 1893, was called "Rio San Lucie". On December 1, 1897, the post office name was shortened to "Rio". The Rio post office was discontinued on March 15, 1902, with the area being taken over by the post office at Goslingville, which was located on the narrow peninsula just north of the present-day Roosevelt Bridge. On April 6, 1904, the Rio post office was reactivated and it continued until October 15, 1927, when it was added to the post office at Jensen, now known as Jensen Beach.
The Rio post office opened in 1897, the earliest record of the town by name (U.S. post office records).
How does Rio rank for history?
Rio is more historic than 28% of U.S. towns. 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 Rio?
9% of Rio’s homes were built before 1940 (Census estimate, ±11.7 points), against a typical 0.6% for a Florida town; the median home was built in 1977.
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 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.
