So there's the question you're asking, the question you're not asking, and the material you linked as an amuse bouche for the question. I'd like to address the last thing first: you've got an undergraduate story problem from a GIS class in 2014. It presumes five nuclear weapons of 25 megatons each, when in fact the Russian strategic arsenal is 1458 strategic warheads of roughly 100-150 kilotons. Yes, they have more tactical weapons than that, but a tactical weapon by definition cannot threaten the United States without being in Canada or Mexico.
As to the question you're asking, the answer is "nowhere."
A full nuclear exchange between the United States and Russia would be 300 megatons or more. The latest climate modeling I'm aware of indicates that a 650kT exchange between, say, India and Pakistan would increase global UV exposure over the northern hemisphere by 30-80% and reduce the growing season by 10-40 days for five years. Should missiles start flying, we're all gonna die. Period. The reason most warheads are under 150kT these days is there's no point in making them bigger. If your goal is to level large chunks of industrial and commercial space, it works just as well as leaving a crater 300 feet deep. Not only that but you can fit more little nukes on a missile, surround them with more decoys and hit more shit. play around here all you want, it doesn't change the fact that the food goes away and never comes back.
As to the question you're not asking, "no, we're not all gonna die."
There were like 70,000 nukes in 1986. They were a preposterous portion of the budget. Nearly all of them are gone now, and we've gone from a world in which most Americans had never met a Russian to a world in which most Americans have watched Russian content on Youtube or Twitch.
I don't know if you're aware of this, but one of the reasons Russia is having such a hard time of it in Ukraine is "tires." And those tires are new - prolly bought from China in the past eight years or so. Russia's nuclear arsenal is a hand-me-down from the Andropov era. They've been trying to modernize but it's been rough going. Yeah they've got all kinds of harum-scarum new doomsday weapons that they love to show off but there's scant evidence that any of them are deployable.
And I mean, the Russians love their children, too. The generalized dread around Russia and its arsenal comes from the idea that Putin is ready to flip over the card table, not that he's a survivor of 50 years of palace intrigue in one of the most ruthless political environments in the world. It's alluring to go "well it's because he's a madman" when you don't immediately understand what's going on, but it's not really a logically defensible conclusion.
I mean, Putin could have taken one look at Kim Jong Un and gone "looks like a good way to go out" and decide Russia's his Hermit Kingdom. He'll be fine. The remaining question is whether the rest of Russia will. What we do know is that Putin has misjudged the situation at least once in the past month or so, and surprised even those close to him. Now - do they love Putin more than they love their children? Or, like the Trumposphere, are they opportunists who know how to get their bread buttered?
I don't know the answer to any of this. But I know it's not "flying nukes."