ZIP Codes in Onawa, IA
Onawa uses 1 ZIP code, all in Monona County. Pick one below for details, or look up the full nine-digit ZIP+4 for a specific street address.
All 1 Onawa ZIP codes
| ZIP | Type | County | Population |
|---|---|---|---|
| 51040 | standard | Monona | 3,500 |
Finding a ZIP+4 in Onawa
Knowing which of these 1 ZIP codes covers an address only gets you partway. The four-digit extension identifies the specific delivery point — typically one side of one block. Two houses facing each other on the same Onawa street almost always have different ZIP+4 codes even though they share all five leading digits.
Appending ZIP+4 to a mailing list?
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