Founding year: the first Port Jefferson post office (Blevins & Helbock, CC0).The full story ↓
History grade
What drives Port Jefferson’s History grade
On its age, its old homes and the National Register, Port Jefferson is more historic than 87% of U.S. towns, #307 of 758 in New York. All 3 inputs are above most U.S. towns; its National Register listings ranks highest and its share of homes from before 1940 lowest.
A
HistoryA character grade: shown, never part of Port Jefferson’s overall grade.
New York towns list more on the Register than most of the country (a typical New York town has 12.3 per 10,000 residents, the U.S. 2.4), so Port Jefferson’s 126 sits above most of its state (78% of New York towns have fewer) while its 102 historic buildings outnumber those of 90% of U.S. towns.
How sure. Graded on any two of the three inputs instead, the letter would range from A− to A. The pre-1940 share is a Census survey estimate (±5.2 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 Port Jefferson’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Fire insurance maps drew every building, what it was made of and what it was used for, so insurers could price the risk of fire. Pick a year, then a sheet.
Sanborn Map Company, via the Library of Congress. Editions published in 1930 or earlier, which are in the public domain.
On the map
Port Jefferson on the map, 1902 to 1967
Every edition of the U.S. Geological Survey’s map of Port Jefferson. Tap a year, or press play to watch the town change.
1902Setauket sheet · 1:62,500
U.S. Geological Survey historical topographic maps (public domain), via Esri’s collection of the scans. The red ring marks the center of Port Jefferson.
Timeline
Port Jefferson, 1834 to 1993
Woven from the archive, old maps, post office records, the National Register and the people born here.
The original settlers of the Town of Brookhaven, based in the neighboring hamlet of Setauket, bought a tract of land from the Setalcott Indians in 1655. The deed included the area of contemporary Port Jefferson along with all other lands along the North Shore from the Nissequogue River eastward to Mount Misery Point.
Port Jefferson's original name was Sowaysset, a Native American term for either "place of small pines" or "where water opens".
when it was removed to a new site in the southern part of the village. This church was set off from the Smithtown circuit in June 1848. The charge then consisted of Port Jefferson, Setauket, Stony Brook and Mount Sinai. Stony Brook was withdrawn from the connection in 1859, and Setauket in 1873.
Text read by machine from the scan; it may contain errors.
Port Jefferson Division, No. 169, Sons of Temperance was instituted in this village April nth 1867, with 26 charter members. It flourished for a few years, and in 1872 had 228 members. It was disbanded in the early part of 1877.
Text read by machine from the scan; it may contain errors.
Scans and text from the Internet Archive. Books published in 1930 or earlier, which are in the public domain.
By decade
Port Jefferson, decade by decade
4 decades in the archive, from the 1830s to the 1880s. Scroll each row; tap a photo for its story.
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.
The Port Jefferson post office opened in 1836, the earliest record of the town by name (U.S. post office records).
How does Port Jefferson rank for history?
Port Jefferson is more historic than 87% of U.S. towns, #307 of 758 in New York. 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 Port Jefferson?
17% of Port Jefferson’s homes were built before 1940 (Census estimate, ±5.2 points), against a typical 27% for a New York town; the median home was built in 1972.
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 (6), Wikipedia, Wikidata and Wikipedia for famous people, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia), Sanborn fire insurance maps (Library of Congress) and old county and town histories (Internet Archive). Archive images are copied here with their credits and licenses, shown on each photo’s page. Refreshed monthly.
1873
1888
