The only area of the United States in which the Democrats have a lead is in the East. In the other three sections of the country, defined as the Midwest, the South, and the West, Republicans have the lead. Gallup doesn't make clear how they define each of those regions.
I'm suspecting that what Gallup calls "the East" is what you and I would call the Northeast - everything north of Virginia and east of Ohio. It is even less clear how the remaining three regions are delineated. They see the U.S. in four regions, I see a minimum of 5 regions with the mountain West being relatively distinct in my eye. Whatever....