In the words of Homer Simpson after he didn’t cast a ballot in an election where the side he wanted lost by one vote: “Sure, like it would have mattered.”
This article details several times that elections or ballot measures came down to one vote, and the consequential results that followed. It’s hard to know how many of these are fully true, but some of them are rather startling. Take this one, which was certainly never taught in any history class I ever attended:
“Henry Clay cast the deciding vote in the Constitutional Convention which admitted Kentucky to the Union as a slave State. If Kentucky had entered the Union as a free State is is hardly doubtful that Missouri would have done the same, and it is conceivable that there might have been no Missouri Compromise, and perhaps even no civil war.”
How Close Votes Influenced World Events: The Sequels to Many Issues Which Were Decided by Single Votes – Are Our Methods of Consulting Public Opinion Faulty?
From November 19, 1916