Montgomery County, Pennsylvania

Montgomery County is a county in Pennsylvania, United States, about 15 miles northwest of
Philadelphia. It had a population of 856,553 at the 2020 census, an estimated 877,643 by 2025, and
covers 487 square miles (1,260 km2) centred near 40°13′N 75°22′W.

Norristown is the county seat; its postal code is 19401. The county holds no cities of its own
— Pennsylvania divides entirely into boroughs and townships, and Montgomery County has 24
boroughs and 38 townships covering every acre of it. It runs on Eastern Time, and its FIPS code is
42091.

Towns & Villages in Montgomery County

Montgomery County has 62 municipalities on record: 24 boroughs and 38 townships. Pennsylvania has
no unincorporated territory, so every place listed here is a fully incorporated municipal
government — there is no CDP or Unincorp. category to apply. Norristown is a borough, not a
city; the county has no cities of its own.

One name repeats on this list. Hatfield Township (18,640 residents) and Hatfield Borough (3,496
residents) are adjoining but legally distinct municipalities with separate governments — the
borough is not inside the township and the two share only a boundary and a ZIP code, 19440. Ambler
and Lower Gwynedd Township both use ZIP 19002 because Ambler’s post office also serves the
surrounding township, not because their boundaries overlap.

ZIP Codes

• 19401 — Norristown (the county seat’s main code; also serves 19403–19409 and 19487–19489)
• 19464 — Pottstown (also serves 19465)
• 19446 — Lansdale
• 19428 — Conshohocken (also serves West Conshohocken)
• 19040 — Hatboro (also serves Horsham Township)
• 18964 — Souderton
• 19002 — Ambler (also serves Lower Gwynedd Township)
• 19468 — Royersford (also serves Limerick Township)
• 19046 — Jenkintown (also serves Rockledge)
• 19072 — Narberth
• 19426 — Collegeville (also serves Trappe)
• 18073 — Pennsburg (also serves part of Red Hill)
• 19405 — Bridgeport
• 18969 — Telford
• 19440 — Hatfield (shared by the borough and the township)

Many of the county’s smaller townships — Towamencin, Springfield, Whitemarsh, Worcester,
Perkiomen and most of the Frederick/Salford group — have no ZIP code of their own; mail there
runs through a neighboring borough’s post office, a common pattern in Pennsylvania where township
governments postdate the postal system that grew up around older borough centers.

Geography

Montgomery County sits in southeastern Pennsylvania’s Piedmont, on the northwest edge of the
Philadelphia metropolitan area. Of its 487 square miles, 483 are land and 4.2 are water, about 0.9
percent. The Schuylkill River crosses the county on a diagonal from northwest to southeast, passing
through Norristown, Conshohocken and Pottstown on its way to Philadelphia; the Perkiomen Creek, its
largest tributary here, drains the county’s northern townships before joining the Schuylkill near
Oaks.

Lehigh County lies to the north, Bucks County to the northeast, Philadelphia County to the
southeast, Delaware County to the southwest, Chester County to the west, and Berks County to the
northwest. Lehigh County, Bucks County, Philadelphia County, Delaware County and Berks County all have live pages on this site;
Chester County borders Montgomery to the west but has no current page here.

Demographics

Montgomery County had a population of 856,553 at the 2020 census, up 7.1 percent from the
799,884 counted in 2010, and the county’s median age is 41.4 years. Lower Merion Township and
Abington Township are the two largest communities, together holding roughly 122,000 residents.
Median household income in the county reached $113,915 in 2024, well above Pennsylvania’s statewide
figure of $73,824 (2023 ACS). Population density works out to about 1,773 people per square mile of
land, among the highest in the state outside Philadelphia itself.

Economy & Local Life

Health care and social assistance is the county’s largest employment sector, with about 69,506
workers, followed by professional, scientific and technical services at 53,225 and manufacturing at
52,473. Pharmaceutical research anchors much of that professional-services employment: GlaxoSmithKline,
Merck and Pfizer all operate major facilities in the county, alongside Lockheed Martin’s defense
operations in King of Prussia. King of Prussia itself, an unincorporated commercial district inside
Upper Merion Township, is home to the King of Prussia Mall, one of the largest shopping and
entertainment complexes in the United States by leasable area. Bryn Mawr College, Haverford College
and Ursinus College are the county’s best-known institutions of higher education, and Main Line
Health and Jefferson Abington Hospital are its largest health care systems.

History

Pennsylvania’s colonial assembly formed Montgomery County on 10 September 1784, carving it out
of Philadelphia County land. It was named for Richard Montgomery, a general killed leading American
forces at the Battle of Quebec in 1775, during the failed invasion of Canada. Norristown became the
county seat that same year.

The county was already settled before its creation — Welsh Quakers established the Merion
and Radnor tracts in the 1680s under William Penn’s original land grants, and German-speaking
Mennonite and Schwenkfelder communities settled the Perkiomen Valley townships in the early 1700s,
leaving place names like Schwenksville still in use today. Valley Forge, the encampment where George
Washington’s Continental Army wintered in 1777–78, sits on the county’s western edge in Upper
Merion Township and is preserved as Valley Forge National Historical Park.

Getting There

Interstate 76 (the Schuylkill Expressway) and the Pennsylvania Turnpike (I-276/I-476) both cross
the county. US 202, US 422 and US 30 run through it as well, along with PA 63, PA 73, PA 113 and PA
309.

• Philadelphia — about 15 miles southeast
• Allentown — about 30 miles north
• Reading — about 25 miles northwest
• King of Prussia — about 20 miles west of central Philadelphia

Philadelphia International Airport, about 20 miles southeast of Norristown, is the nearest major
commercial airport. SEPTA operates several regional rail lines through the county — the Manayunk/
Norristown, Lansdale/Doylestown and Paoli/Thorndale lines among them — plus the Norristown High
Speed Line connecting Norristown to Philadelphia’s 69th Street Terminal.

Frequently Asked Questions

Where is Montgomery County located?
It sits in southeastern Pennsylvania’s Piedmont, about 15 miles northwest of Philadelphia,
bordered by Lehigh, Bucks, Philadelphia, Delaware, Chester and Berks counties.

What is the population of Montgomery County?
856,553 at the 2020 census, with a 2025 estimate near 877,643 — Pennsylvania’s third most
populous county.

How big is Montgomery County?
487 square miles (1,260 km2), of which 483 square miles are land.

What is the county seat of Montgomery County?
Norristown, a borough of 35,748 people, has served as county seat since the county’s formation in
1784.

How many municipalities are in Montgomery County?
62 — 24 boroughs and 38 townships. Pennsylvania has no unincorporated territory, so every
acre of the county belongs to one of them.

What ZIP codes does Montgomery County use?
Dozens, anchored by 19401 (Norristown), 19464 (Pottstown), 19446 (Lansdale) and 19428
(Conshohocken); smaller townships typically share a neighboring borough’s code.

What is Montgomery County known for?
Valley Forge National Historical Park, the King of Prussia Mall, and a cluster of pharmaceutical
research campuses run by GlaxoSmithKline, Merck and Pfizer.

More counties in this state: Towns and villages in Pennsylvania.