What state is abbreviation CA?

CA is the USPS abbreviation for California, the most populous U.S. state.

What does DC stand for in addresses?

DC stands for the District of Columbia, the federal district containing Washington, the U.S. capital.

For the states, USPS two-letter abbreviations and ISO 3166-2:US codes are identical, e.g. CA and NY.

These two-letter codes appear on shipping labels, tax forms, and address APIs — always written in capitals.

Updated: 2026-09-01

USPS prefers these two-letter codes on mail; older lists used longer abbreviations.
Military mail uses AA / AE / AP — not listed here.

What state is abbreviation CA?: CA is the USPS abbreviation for California, the most populous U.S. state.
What does DC stand for in addresses?: DC stands for the District of Columbia, the federal district containing Washington, the U.S. capital.
Are US state abbreviations the same as ISO codes?: For the states, USPS two-letter abbreviations and ISO 3166-2:US codes are identical, e.g. CA and NY.