I'm not sure of the origin of zucchini quick bread, but I wonder if it came out of the WWII Victory Gardens. I decided to make zucchini bread this week, so I spent some time looking up old recipes to compare methods and ingredients. There was no mention of zucchini bread (or squash cake, as I have seen it referred to) in anything I have that's older than about 1940. That may be just a coincidence, or the result of my cookbook selection - I'm not sure.