The idea that an all-out nuclear war will trigger a civilization-ending nuclear winter has been on shaky ground for a while now. It appears the likelihood of it happening to such a degree was based on the political/idealist desire to reduce the nuclear stockpile. [1][2]
For a more realistic view of nuclear war and its survivability, check out [2] (with a foreword by Edward Teller and author's note by Eugene Wigner of Wigner's friend fame).
I agree nuclear winter might not occur or not be all that impactful, however you still will have mass starvation as all supply chains will just disappear, including fuel for power plants. Cities will not be able to supply food and sustain themselves unless in very rare and specific scenarios.
With things like the Iron Dome and Patriot Missile System I'm certain the US has the capability to knock some number of incoming nuclear weapons out of the sky. People in rural and even suburban areas in the US will probably be fine, maybe lose a few years life expectancy due to cancers and the like.
For a more realistic view of nuclear war and its survivability, check out [2] (with a foreword by Edward Teller and author's note by Eugene Wigner of Wigner's friend fame).
[1] https://en.wikipedia.org/wiki/Nuclear_winter#Criticism_and_d... [2] Kearny, C. Nuclear war survival skills