Dashing Through the Prose: The Em Dash

I love the em dash (—). I love the way it looks in text—a long, straight line that drives the prose forward. The em dash can take the place of commas, colons, and parentheses. It's more emphatic than the tiny comma, not quite as emphatic as the colon, and sometimes smoother than parentheses, which can interrupt the flow of the text. The em dash has a will of its own. It stands out, alerting the reader to pause and pay attention to what comes next. The em dash is so named because the length of the dash equals the length of the typed letter "m," but I like to think it earned its name from its multifarious uses.

Here are some of those uses:

Comma alternative

Vladimir slipped away at midnight, as he did during every full moon, to metamorphose into a vampire. [good]

Vladimir slipped away in the middle of the night—as he did during every full moon—to metamorphose into a vampire. [better]

Parentheses alternative

The last time Earl hauled his monthly accumulation of beer cans (all 151 of them) to the recycling bin, he vowed to improve his health by switching to wine. [good]

The last time Earl hauled his monthly accumulation of beer cans—all 151 of them—to the recycling bin, he decided to improve his health by switching to wine. [better]

Here are a few other examples in which an em dash can be substituted to increase the emphasis on the set-off phrase:

The last donut (chocolate cream) sat on the plate, calling my name. [good]

The last donut—chocolate cream—sat on the plate calling my name. [better]

The weary editor, whose eyesight was strained, struggled to notice the difference between a colon and a semicolon. [good]

The weary editor—struggling with strained eyesight—had a difficult time seeing the difference between a colon and a semicolon. [better]