West Mifflin, Pennsylvania Population

Current Population

18,707

Estimated July 1, 2025

-861 residents(-4.4%)since 2020

Annual change-0.7%2024–2025

Latest Official Census

19,589

2020 Census

boroughAllegheny County

Population Over Time

Estimated population changed from 19,568 in 2020 to 18,707 in 2025.

Annual population estimates by year.
Year	Population	Change	% change
2020	19,568	—	—
2021	19,387	-181	-0.9%
2022	19,148	-239	-1.2%
2023	18,979	-169	-0.9%
2024	18,831	-148	-0.8%
2025	18,707	-124	-0.7%

2020 Census (official count): 19,589

Census History

Official Decennial Census counts. Each is an enumeration taken on April 1 of its census year, separate from the annual estimates above.

Official Decennial Census counts by census year.
Census	Population
2010 Census	20,313
2020 Census	19,589

Insights

West Mifflin's population declined 3.6% from 2010 to 2020.
Source: U.S. Census Bureau — 2020 Census Redistricting Data (P.L. 94-171), table P1
How this was determined
Strongest eligible observation in category "change" (score 66.69, confidence 75); chosen from 1 eligible candidate(s).
Compared against: U.S. places
Confidence: 75/100
West Mifflin is Pennsylvania's 32nd-largest incorporated place by population.
Source: U.S. Census Bureau — Subcounty Resident Population Estimates (SUB-EST2025), Vintage 2025
How this was determined
Strongest eligible observation in category "perspective" (score 65.25, confidence 85); chosen from 1 eligible candidate(s).
Compared against: incorporated places in Pennsylvania
Confidence: 85/100

Sources & Methodology

The current population figure is an annual estimate from the U.S. Census Bureau's Population Estimates Program. The 2020 Census is shown separately as the official benchmark.

Current estimate — 18,707 · July 1, 2025

U.S. Census Bureau — Subcounty Resident Population Estimates (SUB-EST2025), Vintage 2025

Official Census — 19,589 · April 1, 2020

U.S. Census Bureau — 2020 Census Redistricting Data (P.L. 94-171), table P1

These figures can differ because the Census and annual population estimates are produced at different times using different methods. Both are shown so you can distinguish the most current estimate from the official Census benchmark.

How the change since 2020 is calculated

Both endpoints come from the same Census Bureau Population Estimates Program release, so the comparison is like for like: 19,568 on July 1, 2020 and 18,707 on July 1, 2025. The change is the later estimate minus the earlier one (-861), and the percentage is that change divided by the 2020 estimate (-4.4%). The Decennial Census count is never used as an endpoint here — it is an enumeration on a different reference date, produced by a different method, so subtracting one from the other would measure the difference between two methods as well as the change in population.