Business letters are usually single-spaced.    From Wordnet, Princeton University. 

There was a single-spaced typed, unsigned sheet inside.    From Wordnik.com.  [Rostnikov's Vacation]

(And yes, it was exactly a one-page, single-spaced document).    From Wordnik.com.  [First Look At Wolfram Alpha’s Impressive Knowledge Computation | Lifehacker Australia] Reference

Mr. Mulcahy's fairly traditional résumé is a page, single-spaced.    From Wordnik.com.  [Ex-NFLer Preps for a Finance Play] Reference

The explosive sections of the 130-page, single-spaced report were ignored.    From Wordnik.com.  [Tom Hayden: New Military Report Acknowledges Signs of Police State in Baghdad] Reference

In fact, it was 300 single-spaced pages, 300 of them, on her work computer.    From Wordnik.com.  [CNN Transcript Jan 22, 2007] Reference

There was two freaking single-spaced pages of songs from the 1940s and 50s.    From Wordnik.com.  [unclebob Diary Entry] Reference

Sixteen pages of single-spaced verbiage will exhaust any reader's patience.    From Wordnik.com.  [When a Lengthy Resume] Reference

In effect, I suspect that it will extend to at least 20 single-spaced pages.    From Wordnik.com.  [Amitai Etzioni: Give Them an Out] Reference

But they have 25 single-spaced pages worth of inventions they accuse Gore of.    From Wordnik.com.  [CNN Transcript - Special Event: SPIN ROOM: Spinning the Third Presidential Debate - October 18, 2000] Reference

Attorneys compiled six hundred depositions-three thousand single-spaced pages.    From Wordnik.com.  [Jewish Women in Civil Rights - Roberta Galler - Interview] Reference

I wrote him a five-page, single-spaced letter explaining to him how I disagreed.    From Wordnik.com.  [The Tyranny of the Majority: Fundamental Fairness in Representative Democracy] Reference

And they will not be single-spaced unless you want the Empress to give up on them.    From Wordnik.com.  [Style Invitational Week 867: Back in the saddle -- breed 'grandfoals' from this week's winners] Reference

Number of single-spaced pages in the Democratic Party's 2008 Iowa Caucus Guide: 13.    From Wordnik.com.  [Kelly Nuxoll: Iowa Caucuses 101] Reference

Near the end of his six-page single-spaced letter he came to the crux of the issue.    From Wordnik.com.  [McCarthyism at Harvard] Reference

Four days later, he gives me four pages of single-spaced analysis of all the pitchers.    From Wordnik.com.  [USATODAY.com - Johnson, Schilling rise to the occasion] Reference

I've got eight pages, single-spaced, of everybody who's said, please have him say this.    From Wordnik.com.  [Briefing By Staff On State Of The Union Address] Reference

The lines should be single-spaced, but a double space should be left between the paragraphs.    From Wordnik.com.  [Military Instructors Manual] Reference

He went on for two single-spaced typewritten pages, tearing the contract apart line by line.    From Wordnik.com.  [Brian Keane: Kagan: She Had Me at Scalia] Reference

All five disks were packed with data, totaling over seven hundred single-spaced pages of text.    From Wordnik.com.  [Clear and Present Danger]

He'd compiled a list of people half a page long, single-spaced and, for a wonder, neatly typed.    From Wordnik.com.  [Hunting Season]

So I wrote this 10-page, single-spaced letter outlining the abuses, sent it to the FBI PR people.    From Wordnik.com.  [The FBI: Inside the World's Most Powerful Law Enforcement Agency] Reference

He printed out two single-spaced pages, zippered them into his backpack, and hopped on his bicycle.    From Wordnik.com.  [Hoot]

One was typed -- both sides, single-spaced -- it seemed on an old typewriter that dropped its "y's.".    From Wordnik.com.  [Analog Science Fiction and Fact]

No. He wrote a 2-page, single-spaced apology and sent it to a columnist at the Cleveland Plain Dealer.    From Wordnik.com.  [Gerald Bracey: First Lady Follies] Reference

They said, what's this guy doing running for President with all this -- look at this single-spaced type.    From Wordnik.com.  [Remarks By The President To The People Of Dover Nh] Reference

Apparently, I find it off-putting to send out an update that is less than 4 single-spaced typewritten pages.    From Wordnik.com.  [granite and chisel] Reference

Moreover, a solid mass of single-spaced typewriting is much harder to read than material that is double-spaced.    From Wordnik.com.  [If You Don't Write Fiction] Reference

It was a short list, unlike in the old days when two columns of names, single-spaced, would fill the entire page.    From Wordnik.com.  [Ellery Queen Mystery Magazine]

Under that, the typing was single-spaced and the open part of many of the round characters was clogged with dirt.    From Wordnik.com.  [Funeral In Berlin]

You can't write 12 single-spaced pages of this kind of history without eliciting some criticism and disagreements.    From Wordnik.com.  [CNN Transcript Apr 14, 2004] Reference

GREG SKORDAS, DEFENSE ATTORNEY: Well, this statement, the one I ` ve got, is a 12-page single-spaced press release.    From Wordnik.com.  [CNN Transcript Jan 5, 2007] Reference

The Chrysler banks are saying that Exhibit A lists all the dealers that will close and it is 42 pages, single-spaced.    From Wordnik.com.  [CNN Transcript May 15, 2009] Reference

The long letter, three single-spaced pages, is articulate and terribly emotional-even raw-sometimes angry but never shrill.    From Wordnik.com.  [Is There No More Magic?] Reference

Weeks documented his allegations in a 39-page, single-spaced affidavit, plus its 22 exhibits totaling 140 more pages of evidence.    From Wordnik.com.  [Andrew Kreig: Siegelman Deserves New Trial Because of Judge's 'Grudge,' Evidence Shows] Reference

In a four-page, single-spaced letter, he makes no less than eight references to "barriers to entry" or "barriers to competition.".    From Wordnik.com.  [Jonathan Spalter: Why Derail the Mobile Revolution?] Reference

Mr. Holder knows that former Attorney General Michael Mukasey had rejected the OPR draft in a scathing, 15-page, single-spaced memo.    From Wordnik.com.  [The Pursuit of John Yoo] Reference

By the next morning, early, he had four single-spaced pages in Latin, and he outlined the blueprint of his papacy, which was very good.    From Wordnik.com.  [CNN Transcript Apr 24, 2005] Reference