there were big cities during the american revolution, you have to remember there hadn't been any expansion west yet so the population was more concentrated
philadelphia (pop 25,000), boston, new york, new jersey (which is a state, but had a pop of 120,000), charleston, etc.
guns were dogshit at the time, hence the whole lining up in rows and shooting at each other, so i doubt they'll play that much of a factor
still think WWI would be more interesting