What is a ZIP Code?
A ZIP Code is a five digit numeric code that identifies a collection of mailing addresses within the United States and its territories to simplify the distribution of mail by the United States Postal Service (USPS).
ZIP Codes are not, by definition, areas but they are the street-based routes the mail carrier travels to deliver the mail. Boundaries can be created based on the location of addresses, but this is an approximation because carrier routes may overlap and portions of the country don’t even have deliverable addresses. To compound the difficulties in creating these areas, the ZIP Codes may not adhere to the boundaries of cities, towns, counties, or states.