Born in New York and raised on the East Coast, I've only ever known butter sticks to be long and skinny, sold in sets of four and stacked as a cube. But it turns out that they do butter a little differently west of the Rocky Mountains. Yes, there's a difference between East Coast and West Coast butter. The regional difference has to do with the size and shape of the packaging rather than the makeup of the butter itself. A 4-ounce stick of butter is just a 4-ounce stick of butter, after all. But on the East Coast, those sticks of butter are long and skinny, while sticks of butter on the West Coast are shorter and fatter; that's why sticks of butter on the West Coast are sometimes called "stubbies."
But there's also a surprisingly fascinating history as to why East Coast butter is different than West Coast butter. Butter used to be sold in one pound blocks, wrapped in parchment paper and packaged in a cardboard box, until 1906, when a big buyer of butter from a restaurant in New Orleans asked if the butter company could sell butter in packs of four quarter-pound sticks rather than one big lump. They obliged, and the sticks were a hit. At the time, the town of Elgin, Illinois was known as the Butter Capital of the World, home to the famous Elgin Butter Company since 1871. It was with their Elgin Butter Cutter that the East Coast butter size was determined, according to a 1948 paper on the packaging of butter, and that's how the name Elgin stick was derived.
It wasn't until the 1960s that the West Coast really got into the butter making game, as reporter Tommy Andres explained on APM's Marketplace. According to John Bruhn, former director of the Dairy Research and Information Center at the University of California, Davis, "...the size of the cube you see is a result of newer equipment purchased at the time to package the butter." And that difference has stuck, so much so that even Minnesota-based Land O' Lakes makes butter in both sizes and ships it out regionally.
For the most part, the difference in butter size doesn't make a difference when you're cooking. After all, if you're whipping or melting or churning the butter, it doesn't matter how it was packaged. Where this whole different sizes of butter thing gets complicated is when you're trying to find kitchen accessories for your butter—like a simple butter tray. If you move out to California from Massachusetts, your butter dish probably won't fit the standard stick of butter. So before you start blaming the butter, or trying to mold it to fit, try getting a new butter dish, maybe even one that'll fit both sizes, just in case.