Punctuation Series: Colons | Commas | Dashes | Semicolons
There are two types of dashes. The em dash and the en dash. The em dash—which this article will be focused on—is the longer of the two. Both em and en dashes are visually and functionally distinct from another similar looking punctuation: the hyphen.
The em dash—hereafter simply referred to as “dash”—serves three purposes:
- To signal a change of thought, meaningful pause or an unexpected interruption.
- To clarify a list or sequence within a sentence.
- To introduce an attribution at the end of a quote.
Dashes as interruptions
While there is ample disagreement about the dash, the general consensus is that its primary function is as a signal of interruption.
The AP Style Guide states that dashes can be used to “denote an abrupt change in thought in a sentence or an emphatic pause.” Patricia T. O’Connor writes that “the dash is like a detour sign; it interrupts the sentence and inserts another thought.” Mignon Fogarty concurs: “A dash interrupts the flow of the sentence and tells the reader to get ready for an important or dramatic statement.”
In most cases, the dash can be substituted with another form of punctuation (such as a colon, commas or parentheses). So the key difference, when using the dash, is that it’s intended to be more dramatic. Because of this distinction, many style guides recommend judicious use of the dash. Peppering your prose with excessive dashes is akin to using too many exclamation marks or writing in all caps. Use the dash sparingly for those moments when your prose needs to pop.
With that in mind, let’s move on to some examples.
First, the dash can be used where commas or parentheses might be used as an aside or interruption in the middle of a sentence. Remember that the dash is considered more jarring than using commas or parentheses, so consider which punctuation achieves the desired effect.
- Example: He made sure to skip bathing and normal hygiene—it was part of an onerous contract—while fully immersing himself in his latest film role.
- Example: The man rushed forward—eyes full of hate—and punched the innocent bystander.
Second, the dash can be used at the end of a sentence, much like a colon, to introduce something dramatic or surprising.
- Example: In front of me was my mortal enemy—the Dark Lord himself.
- Example: Detective Johnson knew could mean only one thing—the serial killer was loose again.
Third, the dash can be used in dialogue to suggest and interruption or the more natural human proclivity to shift gears or thought unexpectedly.
- Example: “If we keep on this road we’ll be there by—look out! Bandits!”
- Example: “Work is fine, I got a raise—wait, when did you move to Los Angeles?”
The dash for mid-sentence lists or series
There is a special case of mid-sentence interruption where a dash or parentheses is obligatory: sentences that include interruptive comma-separated lists (called “appositives”). In this case, the dash is needed to avoid the use of ambiguous commas.
- Example: John enjoys running—Mondays, Tuesdays, and Fridays—when the weather is nice and the mercury is in the low 80’s.
Whether or not a dash or parentheses is used is at the writer’s discretion. In either case, the necessity of the solution is necessary to avoid an overabundance of commas.
The dash for quote attribution
The dash in quotations that use a trailing attribution. You often see these in epigraphs (the short quotations at the start of a book or chapter).
- “You are all a lost generation.” — Gertrude Stein
- “Behind every great fortune there is a crime.” — Balzac
To space or not to space?
There is some disagreement on the necessity of spaces between em dashes. Some style guides advocate for them while others say none are needed. Life is too short to get embroiled in trivialities of this sort—pick a style, go with it, and ignore the haters.
The dash is something of a controversial punctuation mark. Some grammarians consider the dash as too casual for proper written usage. Other observers embrace the versatility of the mark. Regardless of you opinion, the dash does offer an interesting range of possibilities once you learn how to use it. Having a greater range of expressive tools, in my opinion, is always a boon for creativity.
Here are some additional resources that I found useful on the subject:
- The Em Dash Divides (nytimes.com): Fun look at the range of opinions on this “controversial” punctuation mark.
- Em Dash: The Punctuation Guide (punctuationguide.com): No-nonsense overview of the em dash.
- Mad Dash (uhcl.edu): Copy of Ben Yagoda’s opinion piece on the dash originally published in the New York Times in 2012.
- Mechanics of Dialogue: Interrupted Dialogue (grammargeddon.com): The dash really shines in dialogue; this article offers vivid examples.
For comparison, here are the relative widths of each mark: Hyphen: - En Dash: – Em Dash: —
The New York Times Manual of Style states that the en dash should not be used except as a minus sign. The AP Style Guide eschews the use of the en dash altogether. Other guides cite specific uses for the en dash such as sports scores and ranges. Because I prefer the easiest solution to my punctuation problems, I just follow the Times and AP guidelines (granted both guides are intended for journalistic prose, so your mileage may vary). ↩︎
The hyphen is used to join words (like “self-driving”) and for breaking words by syllable (when breaking a word between lines for formatting purposes). ↩︎