More than you wanted to know.

I don't know what different parts have but in the Midwest (Chicago, Milwaukee) and most of the states near by, most homes have both 120v and 220v AC. The 220v is mostly for appliances such as Stoves, Water Heaters, Electric Heat, Central Air Conditioning large window AC's, and in the home shop, certain tools such as HD table saws, etc.

Industrial/commercial areas can also have 3 phase.

So, most everything from enlargers, computers, TV's, lights, drills, and so forth are 110v, sometimes stated as 115v or 120v, even though they are all the same (the voltage varies somewhat in different locations).

I though DC wired homes was back in the beginging of electric use and would be surprised if its in widespread use anywhere in the USA, but then, maybe in DC?