I was myself addicted to soda, and while I never experienced any sort of physical withdrawal symptoms (no headaches, no shaking, etc.), I did experience incredible cravings.
In certain parts of the US, soda is basically thrown in your face everywhere. Every restaurant serves soda as the main beverage. Every theater serves soda, and it's cheaper than the bottled water often and comes with free refills. Every gas station sells soda. Every office has a soda vending machine (or even just free soda altogether, like the one I work in). At lots of fast food places, if you want water, they won't even give you a full-sized cup -- they give you a tiny cup (though it's free) and then you have to hunt for a nearly hidden water tab on the fountain machine.