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BHistory
History · Mercer Township

Mercer Township dates to 1803, and 22% of its homes were built before 1940

More historic than 63% of U.S. towns. What drives it

Below: 23 old photos and papers, maps from 1913 on, and the census since 1820.

1803founded
0on the National Register
22%homes built before 1940
23old photos & papers
Add an old photoShare a memory
From Mercer Township’s archive · credits on each photo
Quick answers

How Mercer Township began

When was Mercer Township founded?

1803

Mercer Township dates its founding to 1803 (Wikidata). The census first counted it in 1820.

First census: 506 in 18202020 census: 993223 years

How historic is Mercer Township?

B

More historic than 63% of U.S. towns, on its age, its old homes and the National Register.

What drives the grade ↓
Founding year: Wikidata. First post office: 1872.
History grade

What drives Mercer Township’s History grade

On its age, its old homes and the National Register, Mercer Township is more historic than 63% of U.S. towns. Its age holds the grade up; its National Register listings pull it down.

B
HistoryA character grade: shown, never part of Mercer Township’s overall grade.
Founding era1803, from Wikidata: founded 1776–1849, an older era than 75% of U.S. townsA−Homes built before 194021.5% of homes (±6.6) · typical PA town 17.7% · U.S. 8.4%B+National RegisterNo listings counted · typical PA town 2.1 per 10,000 · U.S. 2.4C−
All U.S. towns we grade (21,289)Ahead of 63%
NewerOlder

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 Mercer Township’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.

NoteThe founding year comes from Wikidata alone; no second source gives 1803.
How sure. Graded on any two of the three inputs instead, the letter would range from B− to A−. The pre-1940 share is a Census survey estimate (±6.6 points).

Founding year: Wikidata (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 Mercer Township’s past

Read from the archive, the National Register and the record. The page puts what stands out first.

A town in old photos23 old photos, postcards and papers, 1905–1923.Mystery photos18 old photos have no date. Neighbors can guess the decade.Boom and bustPeaked at 2,800 in 1960; 1,982 people lived here in 2020.On the map since 19135 editions of the USGS map, 1913 to 1970. Watch Mercer Township change.
★ What stands out · By decade

Mercer Township, decade by decade

2 decades in the archive, from the 1900s to the 1920s. Scroll each row; tap a photo for its story.

1900s–1920s5 items
CRAIG, F.P. POSTMASTER1905CRAIG, F.P. POSTMASTERMercer PA 1st Presby PHS3541923Mercer PA 1st Presby PHS354Mercer PA 1st United Presby PHS3551923Mercer PA 1st United Presby PHS355Mercer PA 2nd Presby PHS3561923Mercer PA 2nd Presby PHS356Mercer PA 2nd United Presby PHS3571923Mercer PA 2nd United Presby PHS357
1930s–1990snothing yet
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.
Add from your album
Date unknown18 to date
Historic American Buildings Survey, William J. Bulger, Photographer EXTERIOR, MAIN ENTRANCE. - Bell HouseDate?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer EXTERIOR, MAIN ENTRANCE. - Magoffin House, 119 Sout…Date?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer EXTERIOR, WEST ELEVATION. - Bell HouseDate?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer EXTERIOR, WEST ELEVATION. - Magoffin House, 119 Sou…Date?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer, 1936 EXTERIOR, EAST ELEVATION. - Johnson House, Sp…Date?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer, 1936 EXTERIOR, FRONT ELEVATION. - Dr. Beriah Magof…Date?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer, 1936 EXTERIOR, NORTH ELEVATION. - Old Stone Jail, …Date?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer, 1936 EXTERIOR, SOUTH ELEVATION. - Garrett Cenotaph…Date?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer, 1936 EXTERIOR, WEST ELEVATION. - W. J. Robinson Ho…Date?Historic American Buildings Survey, William J. Bulger…Historic American Buildings Survey, William J. Bulger, Photographer, 1936 INTERIOR, DETAIL OF MANTEL, FIREPLACE. - Dr. …Date?Historic American Buildings Survey, William J. Bulger…Bell HouseDate?Bell HouseGarrett CenotaphDate?Garrett CenotaphOld Stone JailDate?Old Stone JailW. J. Robinson HouseDate?W. J. Robinson HouseJohnson House, Springfield FallsDate?Johnson House, Springfield FallsMercer County Bridge No. 2631, Spanning Pine Run at Cribbs RoadDate?Mercer County Bridge No. 2631, Spanning Pine Run at C…Magoffin House, 119 South Pitt StreetDate?Magoffin House, 119 South Pitt StreetDr. Beriah Magoffin House, 116 Venango StreetDate?Dr. Beriah Magoffin House, 116 Venango Street
Today30 recent
US 19-62 sb in Mercer, PA, June 20242024US 19-62 sb in Mercer, PA, June 2024US 19-62 nb in Mercer, PA approaching PA 58 wb split, June 20242024US 19-62 nb in Mercer, PA approaching PA 58 wb split,…PA 58 wb past US 19-62, June 20242024PA 58 wb past US 19-62, June 2024PA 58 wb entering Coolspring Twp. from Mercer, June 20242024PA 58 wb entering Coolspring Twp. from Mercer, June 2…PA 258 nb in Mercer (1), June 20242024PA 258 nb in Mercer (1), June 2024PA 258 nb entering Mercer, June 20242024PA 258 nb entering Mercer, June 2024PA 258 nb approaching PA 58, June 20242024PA 258 nb approaching PA 58, June 2024South Diamond Street2016South Diamond StreetPublic Safety Fail2016Public Safety FailMercer, Pennsylvania2016Mercer, PennsylvaniaMercer, Pennsylvania - panoramio - Idawriter2016Mercer, Pennsylvania - panoramio - IdawriterMercer, PA 16137, USA - panoramio - Idawriter2016Mercer, PA 16137, USA - panoramio - IdawriterMercer, PA 16137, USA - panoramio - Idawriter (6)2016Mercer, PA 16137, USA - panoramio - Idawriter (6)Mercer, PA 16137, USA - panoramio - Idawriter (5)2016Mercer, PA 16137, USA - panoramio - Idawriter (5)Mercer, PA 16137, USA - panoramio - Idawriter (4)2016Mercer, PA 16137, USA - panoramio - Idawriter (4)Mercer, PA 16137, USA - panoramio - Idawriter (3)2016Mercer, PA 16137, USA - panoramio - Idawriter (3)Mercer, PA 16137, USA - panoramio - Idawriter (2)2016Mercer, PA 16137, USA - panoramio - Idawriter (2)Mercer, PA 16137, USA - panoramio - Idawriter (1)2016Mercer, PA 16137, USA - panoramio - Idawriter (1)Mercer historical marker2016Mercer historical markerMercer County Veterans Advisory Council2016Mercer County Veterans Advisory CouncilMercer County Republican Headquarters2016Mercer County Republican HeadquartersErie Street2016Erie StreetAmerican Legion Post2016American Legion PostChristiana Lindsey House2014Christiana Lindsey HouseUS Route 62 - Pennsylvania2013US Route 62 - PennsylvaniaPennsylvania State Route 2582013Pennsylvania State Route 258Pennsylvania State Route 2582013Pennsylvania State Route 258Mercer Reformed Presbyterian Church2012Mercer Reformed Presbyterian ChurchPeter Wolf Toth Statue in Mercer County, Pennsylvania2011Peter Wolf Toth Statue in Mercer County, PennsylvaniaMercer Pennsylvania Pitt Street 20102010Mercer Pennsylvania Pitt Street 2010
Help out

Finish Mercer Township’s story

Most archives stop around 1920. The photos from after that are in family albums, not libraries.

Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
2 of 10 decades. The empty ones are waiting for someone’s album.
Date a photo18 archive items have no date. Guess the decade.+2Retake an old viewCRAIG, F.P. POSTMASTER: stand where they stood+15Share a family photoSign in to add one+10
People over time

Mercer Township, census by census

05001,0001,5002,0002,5003,0001850190019502000Peak: 2,800

Peaked at 2,800 in 1960; 1,982 people lived here in 2020.

21 censuses, 1820–2020.

U.S. Census Bureau decennial counts, from the census table on Mercer Township’s Wikipedia page.

The story so far

Mercer Township, in brief

Wikipedia doesn’t have a history of Mercer Township yet. The photos, dates and memories neighbors add here are how it gets written.

Mercer is a borough in Mercer County, Pennsylvania, United States, and its county seat. The population was 1,982 at the 2020 census. It is part of the Hermitage micropolitan area. The community was named after Brigadier General Hugh Mercer. The Mercer County Court House and Christiana Lindsey House are listed on the National Register of Historic Places.

Mercer Township was established in 1803. Between the 2010 and 2020 censuses its population fell from 1,100 to 993 (-10%).

Intro from Wikipedia. Population: U.S. Census Bureau.

From the old history books

What they wrote about Mercer Township in 1927

Passages that mention Mercer Township, cut from the printed page as they were published.

Harrisville, in Mercer Township, was surveyed for Ephraim Harris in 1825, and he was the first postmaster of the village. The town was incorporated as a borough in 1846. Various industries have sprung up and flourished in this borough.
History of Butler County Pennsylvania1927 · page 563Read the page →
Read the text

Harrisville, in Mercer Township, was surveyed for Ephraim Harris in 1825, and he was the first postmaster of the village. The town was incorporated as a borough in 1846. Various industries have sprung up and flourished in this borough.

Text read by machine from the scan; it may contain errors.
Mercer Township, one of the original thirteen townships of Butler County, established in 1804, was so subdivided in 1854 as to become the smallest of all the final thirty-three townships, but, nevertheless, it has always made a good showing and in some respects has advanced beyond other sections of…
History of Butler County Pennsylvania1927 · page 537Read the page →
Read the text

Mercer Township, one of the original thirteen townships of Butler County, established in 1804, was so subdivided in 1854 as to become the smallest of all the final thirty-three townships, but, nevertheless, it has always made a good showing and in some respects has advanced beyond other sections of larger area. Its citizens are uniformly of a class that has been home-making and home-building, and its lands are notably well tilled and improved, and its natural resources, especially its fine coal deposits, have been developed.

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.

Timeline

Mercer Township, 1803 to 1960

Woven from the archive, old maps, post office records, the National Register and the people born here.

  1. 19th century
  2. 1803
    FoundingMercer Township is established
  3. 1872Post officeThe Forestville post office opens
  4. 20th century
  5. 1905In the archiveCRAIG, F.P. POSTMASTER
  6. 1913On the mapFirst mapped by the U.S. Geological Survey
  7. 1923In the archiveMercer PA 1st Presby PHS354
  8. 1960CensusPopulation peaks at 2,800
On the map

Mercer Township on the map, 1913 to 1970

Every edition of the U.S. Geological Survey’s map of Mercer Township. Tap a year, or press play to watch the town change.

Mercer Township on the 1913 USGS mapMercer Township on the 1939 USGS mapMercer Township on the 1943 USGS mapMercer Township on the 1961 USGS mapMercer Township on the 1970 USGS map1913Mercer 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 Mercer Township.

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.

CRAIG, F.P. POSTMASTER
Retake this viewCRAIG, F.P. POSTMASTER, 1905

Find the spot, match the angle, and add your photo. It becomes the first then-and-now pair on Mercer Township’s page.

Retake this view · +15
Places that used to be

Old corners, places now gone and burying grounds

Old hamlets and crossroads still carry their names on the map.

Hamlets and corners on the map
CarterForestville
Gone or out of use
Harrisville Quarrymine
3cemeteries and burying grounds inside Mercer Township
HarmonyPrairieSaint Anthony

US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).

Stories next door

History across the town line

Each neighbor’s History grade, on the same three inputs.

Marion TownshipIts storyB−Slippery Rock TownshipIts storyBLiberty TownshipIts storyC−Irwin TownshipIts storyC+

Questions about Mercer Township’s history

What year was Mercer Township founded?

In 1803, according to Wikidata. Mercer Township’s post office opened in 1872, and the census of 1820 counted 506 people here.

How does Mercer Township rank for history?

Mercer Township is more historic than 63% 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 Mercer Township?

22% of Mercer Township’s homes were built before 1940 (Census estimate, ±6.6 points), against a typical 18% for a Pennsylvania town; the median home was built in 1971.

Memory lane

What the archives can’t tell you, neighbors can.

Town Square →
Start a conversation
Sources

Where this page comes from

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 (45), the Library of Congress (8), Wikidata (2), 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 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.