ZIP codes in Washtenaw County
31 ZIPs touch Washtenaw County, Michigan. The blue dashed line is the county border; orange ZIPs reach into it.
31
ZIP codes
17
cross the county line
591,880
people in these ZIPs
83
counties in MI
Most people
Washtenaw County ZIP list
More counties in Michigan
- Schoolcraft County7
- Shiawassee County20
- St. Clair County25
- St. Joseph County13
- Tuscola County22
- Van Buren County24
- Wayne County96
- Wexford County13
Questions people actually ask
How many ZIP codes are in Washtenaw County, Michigan?
31 ZIP codes reach into Washtenaw County, including 4 PO Box or single-address ZIPs placed by the town they serve. 17 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Washtenaw County has the most people?
48197 (Ypsilanti) has about 66,525 residents, the most of any ZIP touching Washtenaw County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in Washtenaw 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 Washtenaw 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