What is the difference between a ZIP Code and a ZCTA?
A ZIP Code is part of a USPS delivery address. A Census ZIP Code Tabulation Area, or ZCTA, is an area made for statistics. A point inside a ZCTA does not prove the delivery ZIP for an address.
Use USPS for a delivery address
For a parcel or mailing form, use the full street address in the official USPS ZIP Code Lookup. A PO Box or an organization with its own ZIP may not correspond to the ZCTA at your physical point. Do not fill a required delivery ZIP from a map alone.
A ZIP area can cross a county or city line
Postal delivery and local-government boundaries serve different purposes. The county on a form cannot be inferred from a city mailing name or ZIP alone. County and place maps list the Census ZIP areas they overlap so you can see that distinction.
Read a missing or nearby result literally
Some points lie outside a mapped ZCTA or in a small gap introduced by map simplification. A nearby ZCTA is a nearby area, not a confirmed containing area. Use a precise point for geographic context and USPS for mail.