ZIP Code Lookup & Search
The ZIP Code Lookup Tool is a comprehensive search engine and API that resolves 5-digit United States postal codes to official municipal carrier names, county jurisdictions, Sectional Center Facilities, time zones, and geographic coordinates.
The United States Postal Service manages over 41,000 active 5-digit ZIP codes across 10 national postal zones. Our ZIP Code Lookup tool provides instant, authoritative resolution of any US postal code, delivering detailed postal metadata including acceptable carrier city names, primary county assignments, state postal abbreviations, UTC time zone offsets, Daylight Saving Time rules, and approximate geographic centroid coordinates for mapping.
Tool Parameters & Configuration Options
| Parameter Name | Data Type | Default Value | Functional Description |
|---|---|---|---|
zip |
String (5-digit numeric) | Required |
The 5-digit United States ZIP code to inspect (e.g., 90210, 10001, 60601, 75001). |
Developer Use Cases & Testing Applications
- Checkout Address Autocomplete & Auto-Fill: Implement instant city and state auto-population when customers enter their 5-digit postal code during e-commerce checkout to minimize typing errors.
- Tax Jurisdiction & Carrier Zone Verification: Determine the correct county and state tax boundaries for sales tax calculations and freight shipping rate zone estimates.
- Geocoding & Spatial Range Filtering: Calculate distance radiuses, store locator proximities, and regional service coverage areas based on postal centroid latitude and longitude coordinates.
REST API Integration & cURL Example
You can invoke this utility directly in automated continuous integration workflows, Docker staging scripts, or terminal shells via standard HTTP GET requests:
cURL Request Example
curl -X GET "https://usaddressgenerator.org/api/v1/zip/lookup?zip=90210"Standard API Response (HTTP 200 OK)
{
"status": "success",
"data": {
"zip": "90210",
"city": "Beverly Hills",
"state": "California",
"stateCode": "CA",
"county": "Los Angeles County",
"timezone": "America/Los_Angeles",
"utcOffset": -8,
"dst": true,
"coordinates": { "lat": 34.0901, "lng": -118.4065 },
"scf": "902 (Inglewood SCF)"
}
}Frequently Asked Questions
- How are the digits in a 5-digit US ZIP code structured?
The 5-digit ZIP code represents a hierarchical postal routing system established by the USPS in 1963. The first digit represents a national geographic region from 0 (Northeast) to 9 (West Coast). The second and third digits identify the Sectional Center Facility (SCF), which is the regional mail processing and distribution hub that services a cluster of local post offices. The fourth and fifth digits designate the specific local post office, municipal delivery station, or carrier branch responsible for final mail distribution to homes and commercial businesses.
- Can a single ZIP code span across multiple cities or counties?
Yes, postal ZIP codes are designed strictly for efficient mail transportation and carrier delivery routes rather than municipal political boundaries. As a result, a single 5-digit ZIP code can cross municipal city lines, township borders, and in some rural or suburban areas, even span across county borders. When this occurs, the USPS designates one primary official city name along with several approved acceptable alternative city aliases that postal sorting equipment recognizes. Our lookup engine returns both the primary municipality and all official geographic aliases.
- Does this ZIP lookup tool provide geographic latitude and longitude coordinates?
Yes, our lookup engine returns the approximate geographic centroid coordinates (latitude and longitude) for every valid US 5-digit postal code. These spatial coordinates are ideal for driving store locator widgets, estimating delivery distance radiuses, plotting map pins on Google Maps, Mapbox, or Leaflet canvases, and determining approximate delivery timeframes without requiring expensive commercial reverse geocoding API queries for basic regional mapping and geographic boundary visualization across web applications.
- How do I handle leading zeros when storing ZIP codes in a SQL database?
Always store US ZIP codes as text strings such as VARCHAR(5) or VARCHAR(10) rather than numeric integer types (INT or BIGINT). Many states in the northeastern United States, such as Massachusetts (02138), New Jersey (07030), and territories like Puerto Rico (00901), begin with leading zeros. Numeric database columns will automatically strip leading zeros, converting 02138 into the invalid 4-digit number 2138, which breaks carrier validation routines, shipping APIs, and customer address lookups.