While butter that cows produced had a slightly yellow color, margarine had a white color, making the margarine look more like lard. Many people found it to look unappetizing. Around the late 1880s the manufacturers decided to dye the margarine yellow, so it would sell more. Dairy firms, especially in Wisconsin, became alarmed and succeeded in getting legislation passed to prohibit the coloring of the stark white product….Around 1955, the artificial coloring laws were repealed and margarine could for the first time be sold colored like butter.
For those that actually read the text of these ads and are wondering what in the heck they’re talking about in regard to whether or not a state sells yellow Allsweet…from the Wikipedia article on margarine.