Wisconsin is a big dairy state. Margarine is a corn rather than a dairy product. So what did the dimbulbs in Madison do? Banned margarine.
Cold Spring Shops pointed me to this bit of trivia: until 1967 margarine was illegal in Wisconsin, and people smuggled it across the border from other states.
FWIW: My late mother-in-law was the youngest daughter of a corner grocery store owner. In the New York of the 1930’s and 40’s, there was not an outright ban on margarine (dairy is important in New York, but not dominant). So the rule was that you could sell margarine wholesale, but it couldn’t be colored. Uncolored margarine looks like … Crisco … bright white. So margarine was purchased wholesale in barrels. At the retail level you could either buy it uncolored, or colored with dye packets sent along with the barrel. As a kid, one of my mother-in-laws jobs around the store was to hand mix the dye into the margarine. Not surprisingly, it stained her arms yellow.