Guidelines for Using Semicolons, Colons, and Dashes

Punctation That Separates The Parts of a Sentence

Colon and semicolon on typewriter key
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Some joker once observed that the semicolon is "a comma that has gone to college." Maybe that explains why so many writers try to avoid the mark. They think it's too highfalutin and a little old-fashioned to boot. As for the colon—well, unless you're a surgeon, that one sounds downright scary.

The dash, on the other hand, frightens nobody. As a result, many writers overwork the mark, using it like a chef's knife to slice and dice their prose. The result can be pretty unappetizing.

In fact, all three marks of punctuation—the semicolon, the colon, and the dash—can be effective when used appropriately. The guidelines for using them aren't especially tricky so let's consider the primary jobs carried out by each of these three marks.

Semicolons (;)

Use a semicolon to separate two main clauses not joined by a coordinating conjunction:​​

  • "Weapons are worrisome and expensive; they make everyone edgy."
  • "The debris from tests falls on home ground as well as on enemy territory; it covers the earth like a dew."
  • "Today's weapons are too destructive to use, so they stand poised and quiet; this is our strange climate, when arms are safer than no arms."
    (E.B. White, "Unity," 1960. Essays of E.B. White, 1970)

We can also use a semicolon to separate main clauses joined by a conjunctive adverb (such as however, consequently, otherwise, moreover, nevertheless):

A great many people may think that they are thinking; however, most are merely rearranging their prejudices.

Basically, a semicolon (whether followed by a conjunctive adverb or not) serves to coordinate two main clauses.

Colons (:)

Use a colon to set off a summaryseries, or explanation after a complete main clause:

  • "It is time for the baby's birthday party: a white cake, strawberry-marshmellow ice cream, and a bottle of champagne saved from another party."
    (Joan Didion, "On Going Home." Slouching Towards Bethlehem, 1968)
  • "The city is like poetry: it compresses all life, all races and breeds, into a small island and adds music and the accompaniment of internal engines."
    (E.B. White, "Here Is New York," 1949. Essays of E.B. White, 1970) 

Notice that a main clause doesn't have to follow the colon; however, a complete main clause generally should precede it.

Dashes ()

Use a dash to set off a short summary or explanation after a complete main clause:

At the bottom of Pandora's box lay the final gift—hope.

We may also use a pair of dashes in place of a pair of commas to set off words, phrases, or clauses that interrupt a sentence with additional—but not essential—information:

In the great empires of antiquity—Egypt, Babylon, Assyria, Persia—splendid though they were, freedom was unknown.

Unlike parentheses (which tend to de-emphasize the information contained between them), dashes are more emphatic than commas. And dashes are particularly useful for setting off items in a series that are already separated by commas.

These three punctuation marks—semicolons, colons, and dashes—are most effective when they're used sparingly. Some authors, such as novelist Kurt Vonnegut, Jr., would prefer to do away with the semicolon altogether:

"Here is a lesson in creative writing. First rule: Do not use semicolons. They are transvestite hermaphrodites representing absolutely nothing."
( If This Isn't Nice, What Is?: Advice for the Young, 2014)

But that sounds a bit extreme. Just do as I say, please, and not as I've done on this page: don't overwork these three marks of punctuation.

Practice Creating Sentences with Semicolons, Colons, and Dashes

Use each sentence below as the model for a new sentence. Your new sentence should follow the accompanying guidelines and use the same punctuation contained in the model.

Model 1
"Levin wanted friendship and got friendliness; he wanted steak and they offered Spam."
(Bernard Malamud, A New Life, 1961)
Guideline: Use a semicolon to separate two main clauses not joined by a coordinating conjunction.

Model 2
Your essay is both good and original; however, the part that is good is not original, and the part that is original is not good.
Guideline: Use a semicolon to separate main clauses joined by a conjunctive adverb.

Model 3
"There are three choices in this life: be good, get good, or give up."
(Dr. Gregory House, House, M.D.)
Guideline: Use a colon to set off a summary or a series after a complete main clause.

Model 4
The fortune-teller reminded us that there is only one thing we can count on for sure—total uncertainty.
Guideline: Use a dash to set off a short summary after a complete main clause.

Model 5
Our labors in life—learning, earning, and yearning—are also our reasons for living.
Guideline: For the sake of clarity or emphasis (or both), use a pair of dashes to set off words, phrases, or clauses that interrupt a sentence.