Originally Posted by Rommel49
It seems unlikely that Clem's neighborhood went pear-shaped before Atlanta. All the police and SWAT vans are heading towards the city rather than away from it. Shawn also says something to the effect of "we haven't seen anything this bad since Atlanta a couple miles back".
All the police and SWAT vans were heading toward the city because the zombies had already chowed down on the suburbs, gaining numbers for two days prior. The precedent has already been set in regard to military response times in a US crisis (i.e. Hurricane Katrina).
This thread makes a LOT of assumptions, my theory is just as plausible without blowing 2-day holes in the story.