Great Lakes Zombies. Great idea.
So, I live in Minnesota, so I have a northerners look at the Great Lakes Region.
Population centers for the Great Lakes Region, by size (from Wikipedia)
1. Chicago IL - pop 10 million in the Chicago area, which runs beyond Illinois and into Indiana and Wisconsin
2. Toronto, Ontario - pop 7 million
3. Detroit, MI - pop 6 million
4. Cleveland, OH - pop 4 million
5. Milwaukee, WI - Pop 2 million
6. Ottawa/Gatineau Ontario/Quebec - pop 1.5 million (two cities but one general metro area)
7. Grand Rapids MI - pop - 1.5 million
8. Buffalo NY - pop 1 million
9. Rochester NY - pop 1 million
Smaller cities, less than a million - Hamilton Ontario, Toledo OH, Lansing MI, Kitchener-Cambridge-Waterloo Ontario, London Ontario, Fort Wayne IN, St Catherines/Niagara Ontario, Windsor Ontario, Erie PA (pop 300,000)
I think the vast majority of the metro areas with more than a million would either have burned up (as the virus spreads, power goes out people use lanterns etc, fire departments and police are overwhelmed, once a fire gets started, it's going to spread with no one to fight it, and pretty soon the entire metro area is one of twisted steel girders and blacked house frames in an ash-wasteland) OR are going to be just chalk full of undead.
Some of the smaller cities may be at least more intact and less overrun.
Probably the place where most survivors come from are the smaller cities (25,000-99,000) that are roughly 100 miles or so from the big metro areas that have a more unified community, a sense of belonging, yet big enough to have robust infrastructure and hold together a bit longer, especially if these are the capital cities of the state. They hold together longer, but crumble eventually, and people move lake-ward.
A bit of fun history. Beaver Island, bit island in Lake Michigan. Many of the bigger islands are mainly tourists spots, with the people who live there year round often numbering 500 or so. Same with Bear Island, but in the 1890s or so a bunch of Irish immigrated there and it was the top fresh fish producing area in the USA. It was over-fished eventually, but it seems to me in post apocalypse islands with even a few fishing vessels are going to be efficient safe producers of food (you are unlikely to have a zombie sneak up on you when in a boat in a lake,more likely to be zombie lunch when you are out tending your crops). Maybe the outbreak happened when there were few tourists, or maybe the community chased the tourists off with a 'we'll take care of our own' attitude. Maybe the island had enough fuel that it looks like it will be able to keep 2-3 small fishing vessels out netting for years to come, or maybe other islands are down to pulling nets with rowboats.
A bit of fun history from Bear Island again. A early Mormon offshoot lived on the island before the Irish, and were the majority inhabitants The leader of the church declared himself king of the church and defacto king of Bear island, and started bossing around anyone on 'his' island even those not of his church. Eventually some non-Mormons stood up to him and people from to neighboring islands (Mackinac and St Helena) formed a mob and went over there and de-throned the king and chased the mormons out and took their property. However, it wasn't really about religious intolerance it was about greed...the Mackinac Island folk wanted to control the fishing in that part of Lake Michigan.
So, could one of these small islands with a population of 100-500 have a man step up and declare himself king? Would these islands, relatively safe and with a relatively stable food source be some of the safest places to be, except for other humans? Would at least some of these islands wage war against eachother (maybe a cold war? not very often fighting just animosity and refusal to interact with eachother?) Would some islanders raid other islanders for valuable boat fuel and engine parts?
I imagine 'outsiders', people from other areas traveling might end up on the shores of the great lakes with plans to go to an island not knowing if they are inhabited or not, or just thinking of trying to live on a boat, or just to fish for food. How do the islanders view these people? Do shore communities form? Do any of them get well enough armed and organized to take 20 guys with guns and go in the dead of night and seize power?
Another interesting island is Isle Royale in Lake Superior, bigger than Beaver Island but uninhabited. About 100 years ago it had some caribou, lynx, and coyote living on it. Fur traders hunted the caribou and lynx to extinction. Then some moose swam over to it and thrived. About a thousand moose live there now. Then in the 1950s a pair of wolves crossed the 13 miles of ice and started a moose eating pack. Grew to about 30-40 wolves in about 4 packs, but genetic isolation caused issues. No outside wolf came over until 1990s, then one male made the trek.
So, islands, especially the more northern ones, in harsh winter there gets to be basically solid ice. Now your island isn't so safe. If only twice in about 50 years wolves traveled that far, is it a big risk? Maybe not a huge one, but with more zombies wandering around than wolves in the 1950s-1990s, maybe it is one. Sitting here, it's kind of creepy thinking about a small band of survivors, one guy keeping watch on the broad swath of ice in the bitter freezing cold. What are those little specs in the distance? Are they even real or is staring across the ice all day playing tricks on your mind? Is it a few dozen zombies sniffing the heavy wind and following the scent? Is it a small band of living survivor?
Minnesota forests butt up against Lake Superior, and here is where the last of the US wolves were, a few thousand. Once the Zombie apocalypse sweeps much of humanity away, wolf numbers are bound to explode, and start moving eastward through the rest of the Great Lakes area. Loosing their fear of humans, maybe even developing a taste for them, how big of a threat are they?
Ships get stuck when Lake Superior freezes over, and coast guard icebreaker ships come break them free. What happens when the coast guard is busy trying to help stem the tide, or just falls apart, and ships who were months at sea may not know it, or maybe they are ships trying to leave. There are probably some ships that get frozen in place and the crew abandons them...or dies and becomes zombies. Lots of these ships carry coal, that's got to be a valuable resource. They may carry fuel as well, and even if fuel isn't their cargo, they have fuel tanks for their own engines. That's some very tempting resources to look for. Freaky too, trying to board an abandoned cargo ship, no idea if it is abandoned or if zombies are lurking in the darkened crew quarters.
Here's some cold pictures to go along with this cold great lakes rambling
www.travisnovitsky.com/keyword/hollow%20rock;ice;lake%20superior/i-m4dNPCZ/Ahere's what the survivors look like