Frequently asked questions
Are these the official USPS abbreviations?
Yes. The two-letter codes used here are the official United States Postal Service (USPS) abbreviations, the same ones used in mailing addresses and standardised data entry across the US.
What is the difference between a state abbreviation and a state code?
In everyday use they refer to the same thing — the two-letter USPS code. Historically some states had longer abbreviations (Calif., Mass., Tex.) but the two-letter postal codes became the standard in 1963 when the ZIP code system was introduced.
Are territories included?
Yes. Puerto Rico (PR), Guam (GU), US Virgin Islands (VI), American Samoa (AS), and the Northern Mariana Islands (MP) are all included, as is Washington D.C. (DC).
Is anything uploaded?
No. The entire lookup table is built into the page and runs offline in your browser.