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ZIP codes in Baltimore County

66 ZIPs touch Baltimore County, Maryland. The blue dashed line is the county border; orange ZIPs reach into it.

66

ZIP codes

29

cross the county line

1,223,673

people in these ZIPs

24

counties in MD

Most people

← All Maryland ZIP codes

Baltimore County ZIP list

More counties in Maryland

All 24 counties in Maryland

Questions people actually ask

How many ZIP codes are in Baltimore County, Maryland?

66 ZIP codes reach into Baltimore County, including 9 PO Box or single-address ZIPs placed by the town they serve. 29 of them are only partly in the county and also cover a neighboring county.

Which ZIP code in Baltimore County has the most people?

21234 (Parkville) has about 66,334 residents, the most of any ZIP touching Baltimore County, in the Census Bureau’s ACS 2020–2024 estimates.

Can a ZIP code be in Baltimore 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 Baltimore 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.

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Updated 2026-11-10 · Where the data comes from