I don't think there is anything consistent about the way Americans heat their homes, and I don't think there ever will be. Each region has such different weather that, while there might be consistency within a region, it's unlikely to match a region with drastically different weather concerns.
My brother and SIL live in New England in a house built maybe 30-40 years ago (so relatively new and definitely modern). They have a furnace that runs on oil, because they live in a small enough town that there's no way to get natural gas. An oil-powered furnace ends up being cheaper than paying for it with electricity. The furnace heats water that is fed through copper pipes throughout their house. Radiant heat works far better for heating their home, because it's probably more efficient, but it also doesn't dry the air out. They used to keep their house in the neighborhood of 60 degrees in the winter (and perhaps as low as 55 at night), although now that they have a baby, I imagine they're keeping it a little warmer. They don't have air conditioning, and mostly don't need it.
I, on the other hand, live in the PNW in an apartment. I have basically 3 small forced-air heaters in my walls -- one in the living room, one in the bedroom, and one in the kitchen. They are controlled separately, so I almost never use the one in the bedroom. I don't really have a thermostat, per se, so my husband and I have indoor thermometers. He's not allowed to turn any heat on until it's colder than 68 degrees. Although over the past few weeks, the temperature has been more like 64 or 65, and we've both been comfortable. We also do not have air conditioning, and if we were in a house that had ceiling fans and the possibility of a cross breeze, it would probably be unnecessary. As it is, there are a few weeks every summer where we are very uncomfortable and wish
we had it, but we've never been able to justify buying a window unit.
And then my parents live in Houston, where air conditioning is practically required. Because they already have all the ductwork set up for central air conditioning, I'd imagine that most homes in the region also have forced air heating. It doesn't get used nearly so much (maybe a couple of months out of the year), but it's probably easier to add on to a central air conditioning set-up than to find another way of heating the home. Plus, in a place like Houston, nobody is ever really concerned about too little
Their furnace happens to be run on gas, although I think it's equally common for furnaces to be run on electricity.