Here is a 1990 FEMA prediction, the last one FEMA made during the Cold War.

Could parts of the USA survive a nuclear war?
Not just ‘could,’ parts of the country would. Allen E Hall’s answer shows the destructive capability from Russia’s current arsenal.

In 1990, a FEMA analysis of a 6,139 nuclear strike on the United States (about 3 times Russia’s current arsenal) had more than half of the country’s population not only experiencing less than a fatal shockwave, but experiencing low radiation fallout.

I am copying part of my reiteration of the report from here:

Brian Collins’s answer to What would the world be like after a nuclear war?

Here are screenshots from the report. About half the of the US had a medium to very high fallout risk:

So basically, half of the US population would need to take shelter for a few days to 2 weeks, or risk radiation exposure in a 6,000 warhead strike.

In the high fallout areas, where deadly radiation would be hitting people for more than a week, this is what fatality rates would look like:

The Very High Fallout Risk Areas consist of places like New Jersey, Colorado, Massachusetts, New York City, as well as some rural states with silos or downwind from silos like Nebraska, Montana, North Dakota.

In medium risk areas, the estimate looked like this:

Half of the US population is at risk of a blast of 2 pounds per square inch, a potentially fatal shock wave:

Some segment of the US population within the 2 PSI risk area will die. 50% was about 26% of the 1990s US population.

Today, the percentage would maybe be 10% higher, because the US is a bit more urban now than it was in 1990s, however Russia also has 4,000 fewer nukes than the 6,000 warhead estimate. I think blast casualties would be more than 10–15% of the US population, though much lower at night.

The continuation of this article will reveal real surveys regarding the mortality rate and areas with high risk of attack! So I invite you to read the entire article by accessing the link below: