What Is the Abbreviation of Delaware? Official USPS, AP Style, and Legal Standards

The official two-letter abbreviation for Delaware is DE, as designated by the United States Postal Service (USPS). In traditional literary, journalistic, and legal contexts, the state is abbreviated as Del. The full state name, "Delaware," is not an abbreviation, though written style guides generally require spelling it out in formal prose.

Understanding Delaware State Abbreviations: DE vs. Del.

A common point of confusion among writers, data entry professionals, and legal clerks is whether the full name "Delaware" can serve as its own abbreviation or if a specific short code must be used. In standard English grammar and administrative formatting, a state name itself is never an abbreviation. An abbreviation, by definition, is a shortened form of a word or phrase.

Depending on the context—whether you are addressing an envelope, writing a newspaper article, citing legal precedent, or configuring international shipping data—the acceptable shortened forms for Delaware vary significantly.

The table below outlines the primary recognized codes and short forms used for Delaware across official, technical, and publishing systems:

The USPS Postal Abbreviation: DE

The most widely used abbreviation for Delaware in modern daily administrative work is the two-letter code DE. This identifier was officially introduced by the United States Postal Service in October 1963 as part of a nationwide overhaul to accommodate automated mail sorting and the newly launched Zone Improvement Plan (ZIP) Code system.

Before 1963, state abbreviations varied widely and often included three or four letters with trailing periods. For Delaware, mailers frequently used Del. or De. However, as mechanical optical character readers (OCRs) and automated sorting machinery were implemented in postal facilities, the USPS standardized all state abbreviations into uniform, two-letter, unpunctuated uppercase combinations.

Proper Addressing Guidelines for Postal Mail

When addressing physical mail destined for Delaware, official postal guidelines set forth in USPS Publication 28 (Postal Addressing Standards) dictate specific rules:

1. All Uppercase Characters: Always render the abbreviation as DE using capital block letters. Never write De, de, or D.E.
2. Omit Punctuation: Do not insert periods between or after the letters.
3. Placement Relative to ZIP Code: Place the state abbreviation on the bottom line of the address block, separated from the city name by a single space and followed by the five-digit ZIP Code (or nine-digit ZIP+4 Code).

An example of a correctly formatted USPS address block for a location in Delaware is shown below:

JOHN DOE123 MARKET ST STE 400WILMINGTON DE 19801-1234

Using non-standard abbreviations like Del. on automated mail packages can delay optical scanning algorithms, potentially causing manual handling flags or routing delays at regional processing hubs.

Traditional and Editorial Abbreviations: Del. and AP Style Rules

While two-letter codes dominate logistics and database administration, traditional publishing standards maintain distinct rules regarding state abbreviations. Writers and editors must select the proper format based on their specific editorial framework.

Associated Press (AP) Stylebook

For decades, AP Style mandated the use of standalone traditional state abbreviations in news stories when paired with city names. Under traditional AP guidelines, Delaware was abbreviated as Del. (for example: "Wilmington, Del.").

However, AP Style underwent a major update regarding state abbreviations:

• In Body Text: AP Style requires spelling out the full name of all 50 U.S. states in body text, even when paired with a city. A reporter writing a story must write: "The company moved its headquarters to Wilmington, Delaware."
• In Datelines: AP Style permits standard state abbreviations, including Del., inside news story datelines (e.g., WILMINGTON, Del. —).
• In Tables and Photo Captions: Shortened forms such as Del. or standard postal codes DE are permitted inside tight layout spaces, statistical tables, and photographic credits.

Chicago Manual of Style (CMOS)

The Chicago Manual of Style provides flexible guidance depending on the nature of the manuscript:

• In running text, CMOS recommends spelling out state names completely.
• In endnotes, footnotes, bibliographies, and lists, CMOS permits either the traditional abbreviation (Del.) or the two-letter postal code (DE), provided the author maintains strict consistency throughout the work.

Legal Citations under The Bluebook

In legal scholarship, judicial opinions, and court filings formatted according to The Bluebook: A Uniform System of Citation, state names are systematically abbreviated to conserve space and maintain uniform citation records.

Under Table T10 of The Bluebook, the official abbreviation for Delaware is Del. Legal authors use this abbreviation when citing Delaware state courts, statutory codes, and session laws:

• Delaware Supreme Court Cases: Cited using Del. (e.g., Smith v. Jones, 500 A.2d 100 (Del. 2026)).
• Delaware Court of Chancery Cases: Cited using Del. Ch. (e.g., In re Taxable Issues, 120 A.3d 50 (Del. Ch. 2024)).
• Delaware Code Annotated: Cited as Del. Code Ann. tit. 8, § 101.

Writing DE in a formal legal brief instead of Del. violates standard legal citation standards and may be flagged during editorial review or court filings.

Technical, Data Processing, and International Identifiers

In computer systems, global trade databases, and geographic information systems (GIS), Delaware is represented by specialized technical codes designed to prevent ambiguity across regional and international borders.

• Delaware State Identifiers
  • USPS Postal Code: [DE] (Domestic Mail)
  • ISO 3166-2 Standard: [US-DE] (Global Shipping)
  • ANSI/FIPS Numeric: [10] (Census & Datasets)

ISO 3166-2:US (US-DE)

The International Organization for Standardization (ISO) maintains the ISO 3166-2 standard, which defines principal subdivisions (such as states or provinces) for all countries.

• The ISO code for Delaware is US-DE.
• The prefix US- represents the country code for the United States, while DE specifies the sub-entity of Delaware.

Important ISO Conflict Warning

In the ISO 3166-1 alpha-2 country code standard, DE represents the Federal Republic of Germany (Deutschland). When managing international databases, logistics software, or cross-border e-commerce systems, using an unadorned DE code without the US- country prefix can lead to routing errors, where system logic misinterprets a Delaware address as a destination in Germany.

FIPS 55 and ANSI Numeric State Code (10)

Federal agencies, such as the U.S. Census Bureau and the Federal Bureau of Investigation (FBI), utilize numerical coding systems to categorize geographic data.

• Under the Federal Information Processing Standard (FIPS) and American National Standards Institute (ANSI) INCITS 38:2009 framework, Delaware is assigned the two-digit numeric code 10.
• FIPS numeric codes are sequenced alphabetically by state name (e.g., Alabama is 01, Alaska is 02, Arizona is 04, Arkansas is 05, California is 06, Colorado is 08, Connecticut is 09, and Delaware is 10).

Delaware Corporate Filings and Legal Entity Naming Context

Delaware is internationally recognized as a premier corporate jurisdiction. More than 60 percent of Fortune 500 companies and a vast majority of U.S. initial public offerings (IPOs) are incorporated through the State of Delaware Division of Corporations. Consequently, queries regarding the abbreviation of Delaware often intersect with corporate entity naming rules.

Entity Type Abbreviations vs. State Designation

When registering a business in Delaware, founders must append an official corporate designator to their business name. These suffixes are abbreviations of corporate structures, not abbreviations of the state itself:

• Corporations: Must contain words or abbreviations such as Association, Company, Corporation, Club, Foundation, Incorporated, Institute, Society, Union, Syndicate, or Limited—or their respective abbreviations: Inc., Corp., Co., or Ltd.
• Limited Liability Companies: Must contain the words "Limited Liability Company" or the abbreviations L.L.C. or LLC.
• Limited Partnerships: Must contain the words "Limited Partnership" or the abbreviation L.P. or LP.

Foreign Qualification Notation

When a company incorporated in Delaware registers to conduct business in another state (a process known as foreign qualification), state filing offices frequently require the inclusion of the state of formation in administrative records.

In such documentation, state agencies typically require either the postal code (DE) or the full statutory phrase (State of Delaware). For example, a business operating in Pennsylvania might be recorded as:

Acme Technologies, LLC (a Delaware limited liability company)

Summary Guide to Correct Abbreviation Usage Across Scenarios

To help select the correct format for any scenario, reference the decision matrix below:

Common Misconceptions and Formatting Pitfalls

Understanding how to abbreviate Delaware requires avoiding several widespread errors in administrative and literary writing:

1. Assuming "Delaware" is its Own Abbreviation

Searching whether the "abbreviation of Delaware is Delaware" often stems from seeing full state names listed in dropdown menus or form fields labeled "State Abbreviation." Entering the full name "Delaware" into a two-character database field designed for postal abbreviations will result in a data validation error or text truncation.

2. Using Non-Standard Two-Letter Codes

A common mistake among individuals unfamiliar with U.S. state postal codes is guessing the two-letter combination. Because Delaware starts with "D" and contains "L," people occasionally mischaracterize the code as DL.

• DL is not a valid U.S. state postal abbreviation (though it is used in some international context codes).
• The correct USPS abbreviation is strictly DE.

3. Punctuation Contamination

Combining styles creates non-standard representations. For example, writing D.E. with periods attempts to merge the two-letter postal standard (DE) with traditional punctuated abbreviations (Del.). This form is incorrect across all standard writing guides.

4. Overusing Postal Codes in Professional Prose

Inserting DE directly into formal correspondence, cover letters, or academic essays (e.g., "I attended college in Newark, DE.") is discouraged by standard style manuals. In professional prose, spell out the state name fully: "I attended college in Newark, Delaware."

Frequently Asked Questions

Is the abbreviation of Delaware "Delaware"?

No. "Delaware" is the full, unabbreviated name of the state. The official two-letter postal abbreviation is DE, and the traditional literary/journalistic abbreviation is Del.

What is the official two-letter postal abbreviation for Delaware?

The official USPS two-letter postal abbreviation for Delaware is DE. It must be written in uppercase letters without periods or spaces.

Why is Delaware abbreviated as DE instead of DL?

When the USPS established standardized two-letter state codes in 1963, it assigned combinations using the first letter of the state name paired with a subsequent prominent letter. For Delaware, DE was selected using the first two letters of the name. The combination DL was not adopted by the postal service.

How should Delaware be abbreviated in legal citations?

Under The Bluebook legal citation standard, Delaware is abbreviated as Del. This format is used for state court references (such as Del. for the Supreme Court of Delaware and Del. Ch. for the Court of Chancery) as well as statutory citations (Del. Code Ann.).

What is the difference between DE and US-DE?

DE is the domestic two-letter postal code used within the United States postal network. US-DE is the international ISO 3166-2 standard code used in international logistics, international trade documentation, and global IT systems to differentiate the U.S. state of Delaware from foreign geographic codes (such as DE, which serves as the ISO country code for Germany).

Practical Recommendations

When preparing documents, databases, or mailings involving Delaware, apply these standard practices:

1. For Direct Mail & Shipping: Use the two-letter uppercase postal code DE without periods immediately preceding the ZIP Code.
2. For Formal Essays, Reports, & Resumes: Spell out the full name Delaware in body text.
3. For Legal Filings & Citations: Follow The Bluebook standard and use Del. with appropriate court identifiers.
4. For Web Development & Database Architecture: Store state identifiers using standardized ISO codes (US-DE) or ANSI numeric codes (10) to maintain data integrity across systems.