ZIP codes in Northumberland County
29 ZIPs touch Northumberland County, Pennsylvania. The blue dashed line is the county border; orange ZIPs reach into it.
29
ZIP codes
9
cross the county line
122,838
people in these ZIPs
67
counties in PA
Most people
Northumberland County ZIP list
More counties in Pennsylvania
- Mercer County28
- Mifflin County14
- Monroe County39
- Montgomery County100
- Montour County10
- Northampton County32
- Perry County16
- Philadelphia County86
- Pike County19
- Potter County15
- Schuylkill County61
- Snyder County19
Questions people actually ask
How many ZIP codes are in Northumberland County, Pennsylvania?
29 ZIP codes reach into Northumberland County, including 1 PO Box or single-address ZIPs placed by the town they serve. 9 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Northumberland County has the most people?
17821 (Danville) has about 18,613 residents, the most of any ZIP touching Northumberland County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in Northumberland County and another county?
Yes. ZIP codes follow mail routes, not county lines. Rows marked with a percentage show how much of that ZIP’s land is in Northumberland County. For one address, pin the exact spot on the ZIP finder to see its county.
Where does this list come from?
ZIP areas and their county overlaps come from the Census Bureau’s 2020 ZIP Code Tabulation Area to county relationship file. PO Box ZIPs have no area, so each is placed in the county of the ZIP area nearest the town it serves.
Keep exploring
Updated 2026-11-10 · Where the data comes from