US State Abbreviations

The United States Postal Service (USPS) uses two-letter abbreviations for all 50 states. These standardized codes were established to modernize mail sorting and are now widely used in addressing, government documents, and databases.

Before ZIP codes were introduced in 1963, state names were typically written in full or used informal abbreviations like "Calif." for California or "Fla." for Florida. These weren't standardized and varied widely.

In 1963, alongside the introduction of ZIP codes, the USPS established the two-letter abbreviation system to modernize mail sorting. The goal was to create short, machine-readable codes that would fit easily on envelopes.

Map of US states abbreviations
State Name Abbreviation Notes
Alabama AL First two letters used, no conflicts.
Alaska AK "AL" taken by Alabama, so "K" was chosen as a distinctive second letter.
Arizona AZ "Z" is distinctive; avoids conflict with Arkansas.
Arkansas AR Uses "R" to differentiate from Arizona.
California CA
Colorado CO First and second letters, clear and unique.
Connecticut CT "C" and "T" are distinctive in the name.
Delaware DE
Florida FL
Georgia GA "G" and "A" are intuitive, avoids "GE" (similar to Germany).
Hawaii HI "HA" was avoided due to ambiguity and possible misreading; "HI" uses the first and last letters, making it distinct and easy to recognize.
Idaho ID
Illinois IL
Indiana IN
Iowa IA "IO" was avoided to prevent confusion with the number "10"; "IA" follows USPS patterns for short state names using first and last letters.
Kansas KS "KA" was avoided because it was too visually and phonetically similar to "CA" (California); "KS" uses the first and last letters, making it more distinctive and USPS-friendly.
Kentucky KY "KE" was avoided due to lack of distinctiveness and potential international overlap (e.g., Kenya); "KY" uses the first and last letters, making it punchy and unique among states.
Louisiana LA "LO" was avoided due to lower recognizability and potential confusion; "LA" uses the first two letters and had no conflicts, making it a natural USPS choice.
Maine ME First and second letters.
Maryland MD "M" and "D", distinctive from other M states.
Massachusetts MA
Michigan MI Although "MG" would be more phonetically appropriate, "MI" was already in unofficial use before 1963 and had public familiarity.
Minnesota MN "M" and "N", keeps it distinct from MI and MO.
Mississippi MS "MI" would have been a clearer abbreviation, but it was already taken by Michigan.
Missouri MO "M" and "O", distinguishes from MI and MS.
Montana MT "MO" would have been more logical based on the first two letters, but it was given to Missouri during the initial distribution.
Nebraska NE "NB" avoided to prevent confusion with Canada’s New Brunswick.
Nevada NV "N" and "V", no overlap with Nebraska.
New Hampshire NH
New Jersey NJ
New Mexico NM
New York NY
North Carolina NC
North Dakota ND
Ohio OH
Oklahoma OK
Oregon OR
Pennsylvania PA "PE" was likely avoided due to possible confusion with Prince Edward Island / Peru and other common abbreviations.
Rhode Island RI
South Carolina SC
South Dakota SD
Tennessee TN "T" and "N", unique enough.
Texas TX "T" and "X", X makes it memorable.
Utah UT
Vermont VT "VE" was avoided likely due to international conflicts (e.g., Venezuela) and lower distinctiveness; "VT" uses the first and last consonants, making it clearer and more USPS-friendly.
Virginia VA "VI" was already assigned to the U.S. Virgin Islands; "VA" uses the first and last letters, following a USPS pattern for clarity and uniqueness.
Washington WA
West Virginia WV
Wisconsin WI
Wyoming WY

Interesting Facts About US State Names

Origin of State Names

  • Many state names have Native American origins (e.g., Alaska, Arkansas, Kansas)
  • Some honor European royalty (e.g., Georgia, Louisiana, Maryland)
  • Others are derived from geographical features or Spanish/French terms

Abbreviation Rules

  • All state abbreviations are exactly two letters
  • No two states share the same abbreviation
  • The abbreviations avoid common words (e.g., IN, OR, ME are unique)
  • Most use the first letters of compound names (e.g., New York = NY)

State Name Trivia

  • Rhode Island has the longest official state name: "State of Rhode Island and Providence Plantations"
  • Maine is the only state with a single-syllable name
  • Hawaii is the only state name that uses all vowels

Abbreviation Patterns

Patterns

The USPS followed several patterns when creating abbreviations:

  • First and second letters where possible (e.g., AL for Alabama)
  • First and last letters for distinction (e.g., AZ for Arizona)
  • First letters of compound names (e.g., NC for North Carolina)
  • Avoiding international confusion (e.g., avoiding NB for Nebraska to prevent confusion with New Brunswick)

Special Cases

Some abbreviations required special consideration:

  • The "M" states (MI, MN, MS, MO, MT) needed careful distinction
  • NE was chosen for Nebraska instead of NB
  • NV was selected for Nevada to distinguish it from other N-states
  • GA was preferred over GE to avoid confusion with Germany