Founding year: the first Slippery Rock post office (Blevins & Helbock, CC0). Wikidata: 1841.The full story ↓
History grade
What drives Slippery Rock’s History grade
On its age, its old homes and the National Register, Slippery Rock is more historic than 58% of U.S. towns, #620 of 1,035 in Pennsylvania. Its age holds the grade up; its National Register listings pull it down.
B
HistoryA character grade: shown, never part of Slippery Rock’s overall grade.
Pennsylvania towns list about as much on the Register as the country (a typical Pennsylvania town has 2.1 per 10,000 residents, the U.S. 2.4), so Slippery Rock’s 0.0 sits below most of its state (25% of Pennsylvania 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 range from C+ to A−. The pre-1940 share is a Census survey estimate (±6.5 points). The founding year is the first post office, not a stated founding date; Wikidata’s 1841 falls in the same era, so the grade doesn’t depend on which one is used.
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 Slippery Rock’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Peaked at 4,949 in 1970; 3,081 people lived here in 2020.
18 censuses, 1850–2020.
U.S. Census Bureau decennial counts, from the census table on Slippery Rock’s Wikipedia page.
On the map
Slippery Rock on the map, 1913 to 1970
Every edition of the U.S. Geological Survey’s map of Slippery Rock. Tap a year, or press play to watch the town change.
1913Mercer 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 Slippery Rock.
Timeline
Slippery Rock, 1827 to 1988
Woven from the archive, old maps, post office records, the National Register and the people born here.
The origins of the name "Slippery Rock" date back to colonial times, when members of the Seneca Nation chased European soldiers through the area where Slippery Rock lies today. While crossing a creek, the Seneca lost their footing and slipped on the moss-covered rocks of the creek. The Seneca would later name the creek Slippery Rock.
The post office for Slippery Rock Township was established in 1826 in the Ginger Hill area. The town of Ginger Hill was incorporated as a borough under the name Centreville in 1841, later changing its name to Slippery Rock in 1896 after the Slippery Rock Creek.
Passages that mention Slippery Rock, cut from the printed page as they were published.
History of Butler County Pennsylvania1927 · page 565Read the page →
Read the text
Slippery Rock Borough, formerly known as Centerville, is the principal town of Slippery Rock Township. The first settlers at this place, as shown in the chapter on “Scouts and Pioneer Settlers,” were the Coopers. At that time and for long afterwards, the place was known as Ginger Hill. The post office was established in 1826. In this borough is located the Slippery Rock State Normal School, or teachers’ college, the history of which institution appears elsewhere in this volume. The borough was incorporated in 1841. :
Text read by machine from the scan; it may contain errors.
History of Butler County Pennsylvania1927 · page 511Read the page →
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Euclid Station is located on the divide between Slippery Rock and Muddy Creeks on the Bessemer Railroad, and the place was known for many years as the Center schoolhouse. When the railroad was completed to the summit, it was called Sunbury Station, and shortly after the completion of the road, the name was changed to Euclid. The Painter saw-mill and planing-mill and a creamery were among the first industries of the place, but they were destroyed by fire February 9, 1894.
Text read by machine from the scan; it may contain errors.
History of Butler County, Pennsylvania.1895 · page 305Read the page →
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another farm of 400 acres on the Middle Branch of Slippery Rock creek, where he built a saw mill in 1825 and later a grist mill, the only mill in this section for many years. It was known as Black's mill, and was a familiar landmark in pioneer times. Here he died on October 3, 1832, and his wife, in January, 1864.
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
Slippery Rock, decade by decade
2 decades in the archive, from the 1890s to the 1900s. 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.
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.
1906Sheet 1 of 1
Edition
Sheets
BrickWoodStone
Sanborn Map Company, via the Library of Congress. Editions published in 1930 or earlier, which are in the public domain.
Then & now
Stand where they stood
No then-and-now pairs yet. Take a photo from the same spot as an old one and they appear here side by side.
Retake this viewSlippery Rock Old Main 1, 1893
Find the spot, match the angle, and add your photo. It becomes the first then-and-now pair on Slippery Rock’s page.
The Slippery Rock post office opened in 1827, the earliest record of the town by name (U.S. post office records). Wikidata gives 1841.
How does Slippery Rock rank for history?
Slippery Rock is more historic than 58% of U.S. towns, #620 of 1,035 in Pennsylvania. 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 Slippery Rock?
17% of Slippery Rock’s homes were built before 1940 (Census estimate, ±6.5 points), against a typical 18% for a Pennsylvania town; the median home was built in 1976.
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, Wikidata and Wikipedia for famous people, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia), the US Post Offices dataset (Blevins & Helbock), the USGS Geographic Names Information System, 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.
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