1908 Dragged or drug?

Marti corrected me yesterday when I said I drug something, instead of I dragged it. She's a former English teacher (and a librarian), and my excuse is I was a foreign language major and had almost no college level English (and no English or American literature). My dictionary says it is a "dialect" to use drug as the past tense of drag. So I checked Google, and found this very interesting site which shows by color, where this is commonly used. According to this map, if I'd grown up around here, "drug my feet" would be my preference. But I grew up in northern Illinois, west of Chicago, and that looks like something "the cat dragged in."

American dialects
English language