I assumed the meaning of “bumper crop” meant a large enough crop to reach the bumper of the wagon, truck, whatever was used at the time the phrase came into use.
But, the Farmer’s Almanac says:
Q: Where did the term “bumper crop” or “bumper year” come from?
A: A cup or glass of wine, filled to the brim, used to be called a bumper. Dickens wrote in 1839, “This charming actress will be greeted with a bumper,” meaning a crowded house at the theater.
This site says:
Is it OK to pet the cow?
Dear Word Detective: We recently moved out into the country and have heard the phrase “bumper crop” thrown about. Where did this phrase originate? My husband thinks that there must be something called a bumper at the top of a grain bin and when the bin is full there is a “bumper crop.” What do you think? — Marcia Timmerman, via the internet.
Well, I think the first thing you should do is to warn your husband not to mention his theory to any of the local farmers. Take it from me, nothing launches the average farmer into gales of helpless laughter like the innocent antics of city folks. The first autumn we lived in the country I happened to notice that they were harvesting corn in the field across the road and went over to watch. So shoot me. I was curious. Two years later I am still known around here as “The weirdo who likes to watch corn harvesters.”
Of course, if you just leave out the “gizmo in the grain bin” theory and ask your neighbors what “bumper crop” really means, I’ll bet they won’t know the answer either, because the “bumper” part really doesn’t have anything to do with farming.
“Bumper” in this sense is just a superlative, meaning “unusually large or impressive.” What makes “bumper crop” seem mysterious is that this “jumbo” sense of “bumper” is now very rare anywhere except in the phrase “bumper crop.” But back in the 18th and 19th centuries, it was common to hear shopkeepers talk of “bumper business” in the holiday season or even “bumper traffic” on city streets. “Bumper” as a noun was even used as theatrical slang for a sold-out house at a performance.
The logic of this “large” sense of “bumper” is a little hazy, but a clue may be found in its earliest use. A “bumper” in the 17th century was a large glass of beer or wine that was filled to the brim, i.e., with the liquid literally bumping against the rim of the glass. Such abundance was obviously considered a good thing, as “bumper crops” of just about anything have been ever since.
So it seems it was slang in the 17th-18th century.
Anyway, I’m obsessed with the phrase cause that’s what I want from my garden lol