I saw Alaska mentioned a few times, and having lived here for a few years feel like sharing a few things about Alaska.
Alaska, despite being the biggest state in the entire United States of America, is a very undeveloped state, more so than any other. Most of the land in Alaska is owned by the federal government (The percentage goes to 70% or 75% according to some.). As such, we do not have highways connecting all of the population centers (Oddly enough, many of us have to take a ferry to get to our capital of Juneau.). And even if we could get roads to connect all of Alaska, we have unique problems involved with building, or doing much of anything (Namely one problem that I care to mention, but there are others.). For us to construct on federal land, we have to ask permission and wait for however long it takes for them to approve or deny it. So development is incredibly slow here in Alaska.
The largest population center is Anchorage, and that is 230,000 of our total 700,000 population. After that, the next largest cities are our capital and Fairbanks, both clocking in 31,000 people. But past that, all of the remaining 408,000 people are scattered throughout the entire state, and with a rate of 1.26 people per square mile, there are a lot of areas where there are literally no people. Even with all of this land, we barely use any of it because we simply do not have the population to have a town every few hours from each other. In most cases we have to take bush planes to some of the smaller towns and villages, and the only major way to get into Alaska without getting a plane or a ferry, is to go through Canada on the Alkan Highway, and that highway is long as balls, and the only time to negotiate it easily is during summer or spring.
Winter is cold and it is long, and we basically go through Summer and Winter with no Spring or Autumn. You might think this is awesome, and that we get tons of snow, but such is not true. We do not get as much snow as you think, although that depends where in the 5 regions of Alaska you live (The Interior and North Slope are what I will be referring too, but the West Coast, the South East area, and the Islands usually get pretty heavy snow.). The snow in most places is useless, acting more like watery-icified-sand, with no real value besides covering the ground. The air itself is so dry that the moisture from the snow is literally sucked from the snow that falls, contributing to the uselessness of our snow. Also during winter, we lose a great deal of our day-light. During the earlier and mid-summer months, we have almost 24 hours of straight sunlight. Yes, the sun almost literally never sets. However, because of Alaska's place on the Earth, during winter, we get only about 8 or 6 hours of daylight, and when the sun is down, the temperatures drop even colder. Where I live, the cold is so intense that it prevents much of the exhaust from furnaces and cars from escaping, and visibility and air quality plummet during those days. Although it wouldn't be a problem if most of the people died and turned, it is still an issue (Mostly for those living in natural "bowls".)
I saw someone earlier mention that Alaska has lots of guns and common sense. Yes, this is true. Many Alaskans own guns, and many of us are smart enough to not go outside naked during mid-winter. However, another thing about Alaska is that it is incredibly isolated, especially if you are putting forth an SSSS situation. We import basically all of our foods, and many other things because we don't have them here. That is part of why living up here is so expensive (But we also have higher wages than people in the lower 48 [Any state that isn't Alaska.] to balance this out!). Should mammalian life turn with the affliction, then much of the food that we have up here is going to be gunning to kill us, and thus makes much of Alaska easy pickings for the Silent Lands. I regret to say, but guns and ammunition are not edible. Although the native Alaskans would probably have a better time making it to the year 90 mark, much of Alaska would be Silent Lands and it would stay that way for a loooong time after, especially with how large and rugged we are here.
Although we have a very large military presence here, we do not have as many personnel or toys as we used to. We used to have a cracker ton of F-15's, but the lower 48 put them elsewhere in the states, taking with it all of the personnel who work and maintain those planes. We still have stuff up here, like A-10's and Bradley's, but not as many as there were at one point. And should the refineries, the pipeline, or the rigs lose too many people, there is no way to fuel all of those machines. Even now, the Alaska Pipeline is going to have to be replaced entirely in a few years because the steam from the oil is rusting the pipes from the inside out. So if someone wanted to claim all of the neato weapons of mass destruction we have up here, they'd need to devote a lot of time (And I am talking years if no touches those things for 90 years) and a lot of man power to reclaim those missile and nuke silos, and get those vehicles rolling again. Who is to say they'd even be useful (Although the APC's might be useful.) during the illness.
If anything, people would be surviving the 90 year mark on the coastlines near river mouths, or a little ways upstream. And they'd more than likely be Alaskan Native. (Imply there are no weirdo zombie whales!)
I could have gone on, but I wanted to make tacos, and I like tacos.
To expand on what Stereo said:
Anchorage is an international waypoint for jet travel AND the major transportation hub for Alaska. If you want to go from one jet-capable airport in Alaska to another one that is also in Alaska, you don't fly directly; you go through Anchorage. You also go through Anchorage to get to any other airport in the U.S. All jet passengers use the same airport. In addition, many people drive to jobs in Anchorage from surrounding communities. Chance of infection in Anchorage: 100%; chance of infection in all other towns and cities: 100%. Furthermore, villages without road access tend to have A LOT of small planes, which are often used to go shopping, get medical care, etc., in the cities and towns. Chance of infection in any village or isolated commercial hunting lodge within about 250 miles of a larger community: 80%. (The other 20% are off the road system, get the bad news in time, and fell trees on their airstrips to make them unusable.) I should note here that Alaska is roughly the size of Scandinavia--all of Scandinavia.
That leaves the smaller, really isolated villages, mostly inland in the roadless area called the Bush. The Illness strikes in late fall/early winter. Bush villages are almost cut off from the outside world at this time. The last barge carrying food and fuel came upriver in late summer/early fall. Much of Alaska south of the Brooks Range is suited for farming of hardy crops such as potatoes and kale, with goats and small fruits to round out the diet; people just tend not to unless food is very expensive. There are big gardens/tiny farms in many of these villages because food is
extremely expensive by the time it gets upriver. Also, people still eat A LOT of fish caught in the rivers, which they preserve using low-tech traditional methods. So, they have big stockpiles of food and fuel to see them through the winter of Year 0.
Now what?
After the gasoline, no. 2 fuel oil, machine parts, etc., run out, the survivors have to fall back on traditional methods--but not all of them. Many northern coastal communities traditionally depended on whaling. The ocean is now full of whale-beasts, orca-beasts, walrus-beasts, seal-beasts, polar-bear-beasts, and sea-lion-beasts. North of the big rivers and south of the Arctic coast, people depended on caribou. Oh, look, millions of caribou-beasts hunted by Arctic-grizzly-bear-beasts and wolf-beasts! Plus, these regions have such harsh winters that villagers tend not to keep cats...The river folk have the best chance of survival. The upper Kuskokwim and the entire Yukon run through the taiga, which gets very hot and dry in summer, catching fire easily, and freezes hard enough in winter to turn a monster into a monster-sicle. There are lots of fish. There are also lots of dogs, unfortunately; dogsleds were the only way to get around fast enough without freezing to death in the old days, and people nowadays still have a lot of sled dogs. If one dog gets infected, the entire village is in danger. Also, firearms are really, really a good idea, so hopefully one village can figure out how to make muzzle loaders and trade them with the others after the modern ammunition runs out. A spear thrower or a bow, plus really good aim, might perhaps be useful as well. And of course the people who do keep cats would be trading kittens all over the place. Neighbors are worth their weight in gold in the Bush.
In the Year 90, I would expect to see small pockets of survivors, not all aware of one another, in the southwestern part of Alaska. From Farewell to Sleetmute along the upper Kuskokwim and from Galena to Anvik along the lower Yukon would be the most thickly settled regions, with villages of a few hundred people a few days' travel apart from one another. They would spread out in the summertime to catch fish and huddle up in the winter with cats on duty at all times. There aren't many places for beasts or trolls to hide in this region, so they wouldn't run a risk of swarms, but even one could wipe out a whole community, so they would always be in danger. But, again, the taiga in July burns really, really well. If you have to, set fire to the whole place, get in your boats, and hope the neighbors can take you in until next spring.
ETA: Here's a map of the area I have in mind. If you go too far upriver along the Yukon, you are within flying distance of Fairbanks--not good. South off the map, you're getting close to Bethel--also not good. This region has the best chance of survivors IMO.
http://www.explorenorth.com/library/maps/n-bjonesmap8.htm