County outline
Where Mifflin County is located
Area breakdown
Land accounts for 99.1% of Mifflin County’s measured area and water for 0.9%. Its combined area converts to 1,074.1 square kilometers or approximately 265,413 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 411.037 | 1,064.581 | 263,063.7 |
| Water | 3.671 | 9.508 | 2,349.4 |
| Total | 414.708 | 1,074.089 | 265,413.1 |
How Mifflin County compares
By original Census land area, Mifflin County ranks #54 of 67 in Pennsylvania and #2461 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.629 times the Pennsylvania county-equivalent median of 653.3 square miles. It accounts for 0.9% of the combined county land area in the state.
See the complete Pennsylvania ranking · What counts as a county equivalent?
Population and density of Mifflin County
The Census Bureau estimates that 46,127 people lived in Mifflin County on July 1, 2025. That ranks #1,086 of 3,222 county equivalents nationally and #47 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 46,138, the population has declined by 11 (−0%), compared with +0.4% for Pennsylvania as a whole.
With 411 square miles of land, that is 112 people per square mile (43 per km²), placing Mifflin County #919 nationally for density and #39 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 5.7 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 46,144 | 46,188 | 45,993 | 45,976 | 46,023 | 46,127 |
| Change | — | +44 | −195 | −17 | +47 | +104 |
U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.
Cities and towns in Mifflin County
Mifflin County is divided into 16 municipalities and townships. In Pennsylvania, county subdivisions are local governments, and together they cover all of the county’s land and residents.
The most populous is Lewistown borough, with 8,385 residents (18.2% of the county). The largest by land is Armagh township, at 92.8 mi², or 22.6% of the county’s land. Among those with at least 1,000 residents in 2020, Menno township grew fastest since then (+2.5%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Lewistown boroughCounty seat | 8,385 | −2.1% | 2.03 | 0.5% |
| Derry township | 7,244 | +0.4% | 30.7 | 7.5% |
| Granville township | 4,625 | −0.4% | 40.2 | 9.8% |
| Brown township | 4,187 | +1.8% | 32.8 | 8% |
| Armagh township | 4,088 | +1.7% | 92.8 | 22.6% |
| Union township | 3,684 | +1.2% | 25.5 | 6.2% |
| Decatur township | 2,943 | −0.9% | 45.1 | 11% |
| Wayne township | 2,363 | +0.4% | 48.7 | 11.8% |
| Oliver township | 2,044 | −0.7% | 35 | 8.5% |
| Menno township | 2,035 | +2.5% | 23.7 | 5.8% |
| Burnham borough | 1,970 | −1.1% | 1.052 | 0.3% |
| Bratton township | 1,181 | −1.1% | 32.8 | 8% |
| Juniata Terrace borough | 550 | −2.1% | 0.168 | 0% |
| McVeytown borough | 334 | −1.8% | 0.095 | 0% |
| Kistler borough | 291 | −1.7% | 0.253 | 0.1% |
Show the other 1 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Newton Hamilton borough | 203 | +4.6% | 0.155 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Mifflin County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Mifflin County is a central county of the Lewistown, PA Micropolitan Statistical Area. Mifflin County is the area’s only county equivalent, so the micro area has the same 411 square miles of land. By combined land it ranks #477 of 542 micropolitan areas, and #258 by population.
ZIP codes
14 ZIP Code Tabulation Areas have land in Mifflin County; 11 of them have most of their land inside the county, and the others mainly cover neighboring areas.
1700217004170091702917044170511705417060170631706617075170841709917841
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Mifflin County
Mifflin County shares a land border with 5 county equivalents. It has more land than 3 of them. The largest neighbor is Centre County (1,107.3 mi²) and the smallest is Union County (316 mi²). Together with its neighbors, Mifflin County forms a block of 3,429 mi² of land, of which it holds 12%.
| Bordering county equivalent | Land mi² | Size vs. Mifflin | Compare |
|---|---|---|---|
| Centre County | 1,107.3 | 2.7× larger | Compare |
| Huntingdon County | 874.6 | 2.1× larger | Compare |
| Juniata County | 391.4 | 1.1× smaller | Compare |
| Snyder County | 328.8 | 1.3× smaller | Compare |
| Union County | 316 | 1.3× smaller | Compare |
How big is Mifflin County compared with U.S. states?
Mifflin County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.5 times as much. Pennsylvania’s county land could hold about 109 areas the size of Mifflin County.
Another way to picture it: the same land area would fill a square about 20.3 miles (32.6 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.
State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.
What stands out about Mifflin County?
Mifflin County has more land than 761 of the other 3,221 county equivalents in the dataset.
A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.
Does including water change its rank?
Using land plus water places Mifflin County at #2,519 nationally by total area, 58 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.
Its water share is 0.9%, compared with a national county-equivalent median of 1.2% — 0.3 percentage points lower. This describes the statistical geography’s land/water mix, not flood exposure or developable land.
Closest positions in the national land ranking
These entries sit immediately beside Mifflin County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2460 | Shelby County, Indiana | 411.1 | Compare |
| #2461 | Mifflin County, Pennsylvania | 411 | This county |
| #2462 | Noble County, Indiana | 410.8 | Compare |
Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.
Representative coordinates
The Census internal point is 40.601615, -77.651832. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,064,581,424 m²; AWATER: 9,507,557 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Mifflin County?
Mifflin County, Pennsylvania has 411 square miles (1,064.6 km²) of land and 3.671 square miles of water, for a total area of 414.7 square miles. It ranks #2461 of 3,222 U.S. county equivalents by land area.
Is Mifflin County the largest county in Pennsylvania?
No. Mifflin County ranks #54 of 67 in Pennsylvania by land area. The largest is Lycoming County, with 1,228.9 square miles of land.
What counties border Mifflin County?
Mifflin County shares a land border with Huntingdon County, Juniata County, Centre County, Snyder County, and Union County.
What is the population of Mifflin County?
The Census Bureau estimates Mifflin County had 46,127 residents on July 1, 2025, ranking #1,086 of 3,222 county equivalents. That is 112 people per square mile of land.
What is the county seat of Mifflin County?
The county seat of Mifflin County is Lewistown.
What cities and towns are in Mifflin County?
Mifflin County has 16 county subdivisions (cities, towns and townships). The most populous five are Lewistown borough, Derry township, Granville township, Brown township, and Armagh township.
Is Mifflin County part of a metropolitan area?
Yes. It is a central county of the Lewistown, PA Micropolitan Statistical Area.
How many ZIP codes are in Mifflin County?
14 ZIP Code Tabulation Areas have land in Mifflin County, and 11 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Mifflin County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2.5 times as much land.
How many acres of land are in Mifflin County?
The land measurement converts to approximately 263,064 acres. Including water, total area is approximately 265,413 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.