It’s most likely Washington D.C but I personally want to say Utah because don’t we actually get a confirmation on how many nukes hit Salt Lake City? SLC was hit 13 times! To add on to this, in the journal of the Survivorlist, he said not even the sky-scrapers are left, just a giant scorch mark. I could be wrong though.

I gotta go California for the simple reason that most non-ghoul people there are actually descended from vault dwellers. This doesn’t seem to be true of anywhere else since, even if it’s probably just a writing quirk.

From what we've seen in the games so far, the Capital Wasteland was hit the hardest. But there could be other places that are even more destroyed, like New York City, or Salt Lake City as mentioned above.

The real question is what the f*** was in Salt Lake City that they had to flatten it with a dozen or so nukes?

^ Perhaps they didn't like the Mormon congregation. Jokes on them they were in a Vault (77 perhaps?)

Vault 77 was the vault with the Puppet Man.

^ Ah, I think it was Vault 70 now that I think of it.

The Chinese couldn’t have multiple wives so neither should the Mormons!

If you travel the new California in fallout 1 and 2 it is nearly completely barren only places intact are places where a GECK was used like vault city or locations that are shadows of their former selves like new Reno then again if the tv series is canon then we will see the environment more clearly than we see in fallout 1 and 2