Most style guides ignore the question, but the AP Stylebook has some good advice about when to use the word "on" before a date or day of the week.
One of our listeners wrote in recently with a question. He wanted to know whether to use the word “on” when talking about a date or an event.
Should you say, “I went to the store Saturday,” he asked, or “I went to the store ON Saturday”?
The short answer is that normally, either version is correct. You can use the one that sounds most natural to you or fits best with the rest of the sentence.
Skip ‘On’ When Following AP Style
The Chicago Manual of Style didn’t have anything to say about this topic, nor did most other usage guides we consulted.
The AP Stylebook, however, did weigh in. Its guidance is to avoid using “on” before a date or day of the week — unless not using it would cause confusion. This rule is probably an artifact of AP originally being a guide for print newspapers, where every character was at a premium, and style guidance was sometimes based on saving as much space as possible.
Nonetheless, AP is right in that there are a few place where including the word “on” before a day or date is essential.
Use ‘On’ When a Date Comes at the Beginning of a Sentence
First, you should add the word “on” when the day or date comes at the beginning of a sentence. For example, you could say, “Our book club met Monday.” But if you lead with the day, you should say, “ON Monday, our book club met.”
Use ‘On’ When the Date Could be Confused with a Proper Noun
Second, add it when a day could be confused with a proper name. For example, if you wrote, “I’m looking forward to meeting Jamal Friday,” your reader might think Jamal’s last name is Friday. It would be more clear if you wrote, “I’m meeting Jamal ON Friday.”
In the same vein, you wouldn’t want to say, “I decided to eat Tuesday with an old friend from high school.” Your reader might think you two were zombies, getting ready to eat someone named Tuesday! Better to say, “I decided to eat ON Tuesday with an old friend from high school.”
Those examples are definitely a little silly, but they do show that in rare cases, skipping the “on” before a day or date can cause confusion. Outside of these cases though, and unless you’re following AP style, feel free to use whichever approach tickles your fancy.
AP Stylebook. On. Online version, available by subscription. Accessed October 10, 2019.
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