The butter sticks on the East Coast, often referred to as "Elgins," are longer and thinner, while out West, they're typically shorter and fatter and are called "Western Stubbies."
In terms of time zones, states in the Mountain and Pacific time zones use Western Stubbies, while those in the Central and Eastern time zones, except Texas, use the Elgins.
That idea caught on, and an Illinois company, the Elgin Butter Co., began selling butter molds that produced what is now the long and skinny East Coast butter stick called Elgins.
The reason behind the division still existing might be a historical hangover, with some popular grocery store butter brands actively maintaining this unique cultural difference.
East Coast butter sticks are about 4.8 inches long and 1.3 inches wide and tall, whereas West Coast ones are much stumpier, measuring 3.1 inches long and 1.5 inches wide and tall.
Both types weigh four ounces and contain eight tablespoons of butter, and most packaging has markers to denote what proportion equals a tablespoon, so the shape isn’t a factor.