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The Most Expensive Grammar Mistakes in History

Written by Ryan Van Til

Have you ever submitted a business proposal or sent an email without proofreading it?

Surely a typo here and there doesn't matter in the grand scheme of things, right?

Well, that approach might come back to haunt you. Typos and grammar errors can damage your reputation or even cost you your job.

Cameron Fennell, a fellow proofreader and copy editor, agrees that typos can be disastrous:

"History has shown that the destructive potential of a single incorrect character can be staggering."

Don't believe Fennell? Below are examples of typos, punctuation errors, and misspellings that have had catastrophic effects on individuals, organizations, and governments.

The most expensive typo in history

The world's most expensive typo is generally considered to be a mistake in Mariner 1's guidance system. (Mariner 1 was a probe constructed by NASA to take photos of and gather data from Venus.)

In 1962, shortly following its launch, Mariner 1 was destroyed when a mistake in its guidance system's algorithm sent the rocket off course—and directly toward North Atlantic shipping lanes.

After Mariner 1's crash, the cause of the faulty algorithm was determined to be a missing overbar, which is a line placed over text. Despite the seemingly small size of the overbar, its inclusion in the guidance system's algorithm was essential.

The cost of this typo, when adjusted for inflation, has been estimated to be around $150 million. In addition to the monetary cost, NASA's failure damaged the organization's credibility, and the world was forced to wait a bit longer for up-close pictures of Venus.

Now I know what you're thinking: I'm emailing my boss, not writing an algorithm for NASA. And I don't know what an overbar is, let alone how to use one!

Granted, it's unlikely any typo you make will have a $150 million price tag. Yet the fact remains that typos create inaccuracy and misunderstandings, both of which can have monetary consequences and damage your reputation.

The comma that fruit merchants loved

History is full of examples of expensive typos.

For this error, we have to go all the way back to 1872, when the US government began placing tariffs on imports to boost its revenues. One of the items meant to be taxed was fruit. However, due to a punctuation error, fruit imports were deemed tax exempt for a short period.

The tariff act stated that "fruit, plants" were tax exempt. Merchants (correctly) interpreted this to mean that all fruit and plants should not be taxed. What was intended by the government, however, was that plants for growing fruit were exempt.

How could this have been fixed?

According to the punctuation conventions of the time, there should have been a hyphen between "fruit" and "plants," like this: "fruit-plants."

However, simply removing the comma would also fix the error; "fruit" would then act as an adjective, describing "plants": "fruit plants."

When adjusted for inflation, it is estimated that the comma cost the US government about $40 million. Though this error was costly for the government, fruit merchants were no doubt thankful for the unnecessary comma.

The spelling error that destroyed a reputation

US Vice President Dan Quayle, who served from 1989 to 1993, also experienced the destructive power of a typo.

Unlike the previous examples, this error did not cost Quayle anything in terms of dollars and cents. However, it did greatly damage his reputation—something that no mountain of money can replace.

In 1992, while serving as vice president and campaigning with George H.W. Bush for re-election, Quayle helped moderate a spelling bee. When a participant spelled the word "potato," Quayle announced that the word was misspelled, suggesting the alternate spelling of "potatoe."

Oh, Dan.

The media soon learned of the spelling error, and Quayle was widely mocked. Criticism came from both his political opponents, who wanted to discredit him, and his allies, who called for his replacement.

For his part, Quayle claimed that the word was spelled incorrectly on his cue card. Nonetheless, the damage to his reputation had been done, and he probably still wishes a proofreader had participated in preparing that "potatoe" card.

Though it is unclear what effect the spelling error had on Bush's failed 1992 presidential campaign or Quayle's short-lived presidential bid in 1999, Quayle did describe misspelling the word as "a defining moment of the worst imaginable kind."

Even presidents and vice presidents aren't immune to the effects of typos and grammar errors, which are hard to live down. Proofread, friends!


No one is immune from typos. They happen to everyone eventually, and they can be embarrassing or even expensive.

That's why it's important to minimize their frequency and damage by enlisting the help of a professional editor or proofreader to check your grammar, punctuation, and spelling. The next time you're tempted to hit Send without proofreading, think of NASA, the US government, or poor Dan Quayle, and take another look. You won't regret it!



Image source: NeONBRAND/

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About the Author

Ryan Van Til

Ryan is an editor at Scribendi. His fascination with words and narratives has often led to strong opinions on novels and films. When he’s not debating movies and books on Reddit, he spends most of his time trying to accomplish his lifelong goal of brewing the perfect cup of coffee.