What are USPS Postal Zones?

USPS uses Postal Zones, numbered from 1-9, to estimate the distance between an origin and destination address. Zone 1 is a local shipment, and Zone 9 is the furthest possible distance between locations for a domestic shipment. Rates for most USPS services will vary based on the zone of the shipment's recipient address.

For your convenience, the USPS provides a zone lookup tool based on ship from and ship to zip codes.

When you request a rate in the ShipEngine API with USPS services, you might get a value back for the zone in the response. For example:

    "zone": 5,   
    "package_type": null,   
    "delivery_days": 3,   
    "guaranteed_service": false,   
    "estimated_delivery_date": "2020-04-11T00:00:00Z",   
    "carrier_delivery_days": "3",   
    "ship_date": "2020-04-08T00:00:00Z",   
    "negotiated_rate": false,   
    "service_type": "USPS First Class Mail",   
    "service_code": "usps_first_class_mail",   
    "trackable": true,   
    "carrier_code": "endicia",   
    "carrier_nickname": null,   
    "carrier_friendly_name": "Endicia",   
    "validation_status": "valid",   
    "warning_messages": [],   
    "error_messages": []