What’s the deal with people saying, “on yesterday”? I hear it creeping into the language with increasing frequency as a phrase to show time. Like “on Tuesday” or “on my birthday”. As long as I’ve lived I have never associated the preposition “on” with “yesterday”. All I’ve ever said, or heard until recently is simply, “yesterday”.
Stuff didn’t happen on yesterday. It all happened yesterday!
On is primarily a preposition to show position above or supported by. The book is on the table. We knelt “on” our hands and knees.
Used to indicate figurative or abstract motion toward, against, or onto:going on six o’clock; came on the answer by accident.
Writers use the preposition “on” to show proximity: A sleepy little town on the border.
Writers use it to show actual motion: The march on Washington, or The Army was on the move.
Wordnik (where these references came from) offers a bunch more uses of on, even one for a specific date: “On December 4.” But it says nothing about the using “on” with “yesterday”. My friend Miriam Webster didn’t have anything to add to Wordnik ‘s usage rules either.
The grammatical rule, in my opinion, is: when mentioning or planning an activity or telling someone about something that happened in the 24-hour period just before the last occurrence of 12:00 midnight, use the adverb “yesterday” and not the prepositional phrase “on yesterday”. You will cut the word count by one word and eliminate a prepositional phrase. And any time you can cut word count or drop a prepositional phrase you improve your writing. You will also avoid the embarrassment caused by the use of this grammatical faux pas.