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What are the largest counties in Pennsylvania?

Philadelphia County is the largest county in Pennsylvania, with 1,574,281 residents in 2025 (Census PEP). Allegheny County (1,225,035) and Montgomery County (877,643) come next.

Data as of 2025 · updated

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All 67 Pennsylvania counties ranked

Pennsylvania counties ranked by population
RankCountyResidents 2025Change 2020–25
1Philadelphia County1,574,281−1.7%
2Allegheny County1,225,035−2.0%
3Montgomery County877,643+2.4%
4Bucks County647,828+0.3%
5Delaware County580,937+0.8%
6Lancaster County563,159+1.9%
7Chester County557,116+4.2%
8York County473,197+3.6%
9Berks County440,072+2.7%
10Lehigh County384,383+2.7%
11Westmoreland County349,324−1.4%
12Luzerne County332,126+2.1%
13Northampton County324,411+3.7%
14Dauphin County293,351+2.3%
15Cumberland County277,270+6.5%
16Erie County265,832−1.8%
17Lackawanna County216,502+0.5%
18Washington County210,802+0.7%
19Butler County200,169+3.2%
20Monroe County167,179−0.7%
21Beaver County166,032−1.1%
22Franklin County160,652+3.0%
23Centre County157,393−0.4%
24Lebanon County146,380+2.2%
25Schuylkill County145,085+1.5%
26Cambria County128,968−3.2%
27Fayette County123,021−4.3%
28Blair County119,541−2.5%
29Lycoming County112,587−1.3%
30Mercer County107,860−2.4%
31Adams County107,594+3.6%
32Northumberland County89,920−1.8%
33Lawrence County83,911−2.4%
34Indiana County82,878−0.3%
35Crawford County81,792−2.4%
36Clearfield County78,100−2.9%
37Somerset County72,004−2.7%
38Columbia County66,193+2.3%
39Carbon County65,868+1.7%
40Armstrong County63,698−2.7%
41Pike County62,808+7.2%
42Bradford County59,600−0.6%
43Wayne County51,703+1.1%
44Venango County49,346−2.0%
45Bedford County47,480−0.2%
46Perry County46,806+2.1%
47Mifflin County46,127−0.0%
48Jefferson County43,255−2.8%
49Huntingdon County43,001−2.4%
50Union County42,313−0.8%
51Tioga County40,502−1.3%
52Snyder County39,655−0.2%
53McKean County38,984−3.5%
54Susquehanna County38,237−0.3%
55Clinton County37,870+1.3%
56Warren County37,038−3.8%
57Clarion County36,680−1.4%
58Greene County33,885−5.5%
59Elk County29,926−3.3%
60Wyoming County25,790−0.9%
61Juniata County23,403−0.3%
62Montour County17,868−1.4%
63Potter County15,897−3.0%
64Fulton County14,483−0.7%
65Forest County6,614−5.1%
66Sullivan County5,856+0.6%
67Cameron County4,211−7.0%

How this is ranked

The Census Bureau's July 1 resident population estimates for 2025, largest first, with the change since 2020. Counties with fewer than 1,000 residents are not ranked. Areas without an estimate for the same year as the others are not ranked.

Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025). Figures come from public federal statistics and are informational only, not investment advice. Check the source before relying on a number. Methodology: how ranks and figures are built.

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Questions

What is the largest county in Pennsylvania?

Philadelphia County is the largest county in Pennsylvania, with 1,574,281 residents in 2025 (Census PEP). Allegheny County (1,225,035) and Montgomery County (877,643) come next.

How is this ranking calculated?

The Census Bureau's July 1 resident population estimates for 2025, largest first, with the change since 2020. Counties with fewer than 1,000 residents are not ranked. Areas without an estimate for the same year as the others are not ranked.

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