Let's not forget that with sanitation efforts now ended, insect population like mosquitoes are going to explode. West Nile, yellow fever, and malaria are going to explode again in the south amongst the surviving population. 

I'm not sure I agree with the idea of malls and stores, and emergency centers having much food or supplies. If you ever study how fast the shelves of a supermarket empty when there's an emergency coming or on-going, in a situation like a zombie outbreak, its going to go even faster. Same is true for gas stations, especially as logistics break down. Who wants to deliver a load of stuff to their local Walmart when there could be zombies trying to chew my little girl's face off -right now-? What's more important? Also, how long am I going to be stuck in this traffic? 

And that's before the looting starts and people start taking matters into their own hands. The cities would be pure chaos in a very short time, as police, fire, and emergency medical services are overrun. National guard gets called in along with FEMA and the CDC,but there's very little they could do. If it was one state, sure, it might not be such a big problem. It seems that every state would be having issues, or at least the major cities in short order. Which means that their resources are spread pretty thin. Martial law would probably be declared very shortly with active military moving into the cities, coordinating with whatever services were left. They would probably start engaging in combat operations and sanitization operations, much like is depicted in Season 2 of The Walking Dead. They'd be dropping napalm and setting up combat cordons. 

However, it wouldn't be terribly effective, besides White Phosphorous. Military trains to shoot center mass at long to medium distance. It's drilled into them all the time. Most of the time they use burst or automatic fire as a three round burst through the chest is pretty much a bad day for anyone, and is probably the last bad day they'll ever have. When they start to shoot and the bullets pass through with no notable effect, a good number will panic and start shooting wildly. Even when they figure out headshots work, it's only going to be disciplined shooters that make it work. Expert units like SEALs, Rangers, Delta, Green Berets, Marine RECON, CavScouts, and so on will probably fare much better, or those with combat experience will probably do alright. Which means that there will be 'civilians' who handle themselves, as well as active units that are stateside that will probably do well. The military could do a number of things to increase their effectiveness, but it is likely they will try to engage on the ground, instead of from elevated positions that have been barricaded off, which leaves them in reach of the massive groups of walkers. 

Now, enterprising units who think and decide to take the high ground and take a building, put a rifleman in every window above the second or third floor could be highly combat effective. Perhaps the tactic would spread to other units. If so, there's a fighting chance, especially if choppers aren't used for medivac but resupply. Drop off beans, bullets, and water, take the ones that haven't been injured by the biters, but may have been injured in another way, rotate in fresh troops. 

Sorry, off on a tangent. Anyway, I think the shelves in stores would empty out very very fast, especially since it's a SHTF situation that is WrOL (without rule of law). 

Maine could be good during hte warmer months, but they have really harsh winters. Life or death stuff. Just a thought. 

Still looking for more, and no, Fallen dear, my long part of this post isn't an attack on you or anything. It's just a commentary on goverment inefficiency/inadequacy in a situation like that, especially in a world with no zombie culture.