ZIP codes in Lake County

14 ZIPs touch Lake County, South Dakota. The blue dashed line is the county border; orange ZIPs reach into it.

ZIP codes

cross the county line

26,602

people in these ZIPs

counties in SD

Most people

← All South Dakota ZIP codes

Lake County ZIP list

More counties in South Dakota

All 66 counties in South Dakota

Questions people actually ask

How many ZIP codes are in Lake County, South Dakota?

14 ZIP codes reach into Lake County. 12 of them are only partly in the county and also cover a neighboring county.

Which ZIP code in Lake County has the most people?

57042 (Madison) has about 7,756 residents, the most of any ZIP touching Lake County, in the Census Bureau’s ACS 2020–2024 estimates.

Can a ZIP code be in Lake 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 Lake 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