Oh, you knew this one was coming. Pretty much as the title - what’s the first American city that pops into your head, or the second if the Big Apple comes to mind first?
Included the next 30 most populous, according to wiki.
I’ve been playing the hell out of Fallout 4 so it’s Boston for me.
Columbus, Ohio. (I lived there for 12 years.)
San Francisco.
Beason, Illinois
Also Columbus, since I’m typing this from downtown.
My hometown popped in to my head first. Memphis, TN.
Crows Landing, Ca., Pop. 355, area 3.169 sq. mi.
Chicago, the 2nd best city after New York City.
Yes, definitely Columbus, Ohio.
Seattle, WA - I’m sure this is related to whatever large city is closest to you? Second choice would be Washington, DC - which I’ve also lived in. Maybe it’s just me.
Chicago, of course. Why do you think it’s called the “Second City?” 'Cause it’s the second one you think of after New York.
I was born and grew up in New York; Chicago was what first came to mind for me (though I’ve lived in Austin TX, another city on your list, for over 11 years…)
Atlanta cause it’s my home state. Miami cause it’s the nearest big city.
Youngstown, Ohio.
It’s the largest city in the region, and only fifteen minutes away to the city limits.
Madison, WI, as a friend is there.
Boston, no idea why!
When I read the question Houston just popped into my head. No idea why and I’m kind of surprised as I can’t think of any associations at all. It’s not a place I often think about.
L.A., because I was born and raised there. Isn’t that what anyone from the U.S. would do; think of their hometown (or the closest big city to it)? Of course that doesn’t explain don’t ask’s response. Weirdo. 
Columbia SC, because it’s currently the closest city.
Los Angeles. I don’t know why. I’ve never been there and I’m nowhere near it.