As a convention of written language, punctuation marks function to ensure the clarity of writing for readers and writers. There are three rules for using colons as punctuation marks in written American English:
- Joining related verb clauses
- Joining other verb clauses
- In series with commas
The following sections explain and provide examples of the punctuation rules for semicolons in written English.
Join Related Verb Clauses
Use a semicolon to join to related verb clauses of equal emphasis. Also called a main clause, independent clause, superordinate clause, or matrix clause, a verb clause is a clause that contains both a subject and a predicate and that functions as a complete sentence. For example:
- She helped the committee as much as she could; she even searched the back issues of the newspaper to find evidence.
- The baby rarely falls to sleep this early; I think she is afraid she might miss out on something.
- Winter storm conditions have made travel next to impossible; almost all of the major highways are completely covered in snow and ice.
Do not use a semicolon to connect two unrelated verb clauses.
Join Other Verb Clauses
Use a semicolon to join two verb clauses if the second clause starts with an adverb or short parenthetical that functions as a transition between the two sentences. For example:
- We have paid our dues; therefore, we expect all the privileges listed in the contract.
- All campers should bring many backpacking items; for example, sleeping bags, metal pans, and warm clothing will make the trip more enjoyable.
- If he can, he will attempt that feat; and if his wife is able, she will be there to cheer him on.
Series Containing Commas
Use a semicolon to separate items in a series in which the items already include commas. A series is a list of three or more items. Place a semicolon after each item but the last in the series including before the coordinating conjunction. The seven coordinating conjunctions in English are and, but, for, nor, or, so, and yet. For example:
- My favorite places to travel are Chicago, Illinois; Wichita, Kansas; Forks, Washington; and Mobile, Alabama.
- We need to buy potatoes, cream cheese, and butter for the mashed potatoes; brown sugar, honey, vinegar, and mustard for the ham glaze; and cherries, pineapple, and marshmallows for the fruit salad at the store.
- The planning committee included George O’Drake, president of the bank; Cheryl Martin, head of the grocery association; Jeff Layzell, editor of the local paper; and Myra Brown, dean of the English department at the university.
Do not use a comma to separate only two items that already include commas.
Punctuation marks are a convention of writing that helps readers and writers more clearly understand writing by ensuring the clarity of written language. Semicolons perform three basic functions in written American English: join two related clauses, join two clauses in which the second begins with an adverb or parenthetical, and separate items that contain commas in a series.
Faigley, Lester. 2003. The Brief Penguin Handbook. New York: Pearson Longman.
Gibaldi, Joseph. 2003. MLA Handbook for Writers of Research Papers. 6th ed. New York: The Modern Language Association of America.