When you need to write out the Keystone State in professional correspondence, knowing the correct abbreviation prevents basic mistakes. The official two-letter postal code is PA, written in capital letters without periods. While casual writing often introduces variations, formal documents and official style guides demand precision.
The primary search intent behind looking up this abbreviation usually comes down to formatting compliance, postal address standards, or journalistic style. Writers often wonder when to use the postal abbreviation versus traditional state abbreviations, or how to punctuate the abbreviation in legal documents. This guide breaks down the rules for using the PA abbreviation correctly across professional settings, official correspondence, and style-conscious publications.
Postal Standards and the Two-Letter Code
The United States Postal Service established two-letter state codes to streamline mail sorting and automated processing. For Pennsylvania, that code is strictly PA.
You should always use this two-letter format when writing a complete mailing address that includes a street address, city, and ZIP code. Using older abbreviations like "Penna." or "Penn." causes automated sorting machines to flag the mailpiece for manual review, which delays delivery. Further details on this are covered by Associated Press.
- Always capitalize both letters: PA.
- Never add periods between or after the letters.
- Separate the city name from PA with a single comma, followed by one space and the ZIP code.
For example, a standard business envelope addressed to the state capital should look like this:
Office of the Governor 508 Main Capitol Building Harrisburg, PA 17120
When formatting mailing labels, keeping the state code uppercase and unpunctuated ensures maximum compatibility with modern postal equipment.
Journalistic and Professional Style Guidelines
While the postal code works best for mailing addresses, different rules apply when you write prose, news articles, or academic papers. Major style guides approach state abbreviations quite differently from the postal service.
Associated Press Style
The Associated Press stylebook sets the standard for journalism and many corporate communications. In AP style, you do not use the two-letter postal code within running text. Instead, PA is spelled out entirely as Pennsylvania when it stands alone. When the state name follows a city name within text, AP style historically used traditional abbreviations like Pa., though modern usage often favors spelling out the state name entirely to avoid confusion.
- Correct AP style in text: The conference took place in Philadelphia, Pennsylvania.
- Incorrect AP style in text: The conference took place in Philadelphia, PA.
Chicago Manual of Style
For book publishing, academic papers, and long-form nonfiction, the Chicago Manual of Style recommends spelling out state names entirely within normal prose. If you must include a state name in a source citation or a tabular list, Chicago permits the two-letter postal codes, provided you use them consistently throughout the entire document.
Legal and Official Government Documents
Legal drafting, court filings, and official state government documents require strict adherence to specific formatting rules. In legal briefs, the Bluebook citation system dictates how you abbreviate state names.
When citing court cases or drafting contracts within Pennsylvania, legal professionals follow specific tables to abbreviate case reporters and jurisdiction markers. However, general correspondence from state agencies relies on standard business writing rules, prioritizing clarity over stylistic flair.
When you draft contracts or agreements, define the state at the outset—such as "this agreement is governed by the laws of the Commonwealth of Pennsylvania"—and thereafter refer to it simply as the "State" or "Commonwealth" to avoid repetitive abbreviations.
Common Mistakes to Avoid
Writers often make a few recurring errors when dealing with state abbreviations. Avoiding these pitfalls keeps your writing polished and professional.
- Mixing postal and prose styles: Don't drop postal codes into the middle of a sentence. Save PA for addresses, tables, and data lists.
- Adding periods: Writing "P.A." or "Pa." in modern mailing formats creates outdated and non-standard addresses. Stick to clean capital letters.
- Overusing abbreviations in creative writing: In narrative writing, abbreviating state names pulls the reader out of the story. Spell out the full name unless space constraints in a table or sidebar make it impossible.
- Confusing PA with other codes: Double-check your data sets to ensure PA doesn't get swapped with similar two-letter codes like ME, NE, or PR during data entry.
Frequently Asked Questions
What is the traditional abbreviation for Pennsylvania?
Before the USPS introduced two-letter postal codes in 1963, Penna. and Pa. served as the standard abbreviations in general writing and journalism. Today, you will rarely see "Penna." outside of historical documents, while "Pa." still appears occasionally in specific publishing contexts.
Should I use periods in the PA abbreviation?
No. Official postal guidelines and modern style guides omit periods entirely. Write it simply as PA.
Is PA used for both the state and the commonwealth?
Yes. Although Pennsylvania is legally a commonwealth rather than a state, it functions identically to a state within the US postal and administrative systems. The abbreviation PA applies universally to all official references.
How do I format PA in international shipping?
When sending mail to Pennsylvania from another country, you should include PA followed by the ZIP code, and add USA on the final line beneath the city, state, and ZIP code combination to ensure international postal workers route the item correctly.
