I've been in Ohio more than usual the last few months, and so have shopped some of the local purveyors. Ohio is a control state. Through it no longer runs the retail stores, its retail agents are very limited in terms of what they can do, so if you've seen one Ohio liquor store, you've seen them all.
I was surprised to see how big a selection of North American blends they sell, the Americans and Canadians right next to each other. The Canadian selection seemed about normal, but I was surprised by the large selection of American blends. All of the major brands were represented with several facings and at least 750 ml and 1.75 L sizes, and sometimes liters. Here in Illinois, even a big liquor store will have only Seagrams 7 in a 750ml, then three or four other brands (Kessler, Thompson, Philadelphia, etc.) in handles only. In Kentucky, you see them even less.
In 99 Drams, Kate Hopkins talks about the ubiquity of blends in the Pittsburgh of her youth, especially Imperial. Then as now, they're usually mixed with a soft drink.
Nationally, American blends sell about 1/10th what American straights do, but I think the Great Lakes region is the blends heartland.