America loves their Mountain Dew. From gamers to grandmothers, you'll find people from all walks of life who can't get enough. In fact, Mountain Dew was the fourth most popular brand of soda in the United States in 2010, while Diet Mountain Dew was the eighth most popular. Mountain Dew has a complicated history. It originated as a whiskey chaser in Knoxville, Tennessee in the 1940s. But at that time, it only had a light flavor that was reliant on lemon and lime.