A couple of bloggers have postings about being prepared in an emergency or in the case of a disruption of services... see Mr. B's post here and Tam's post here. Having lived in Boston for a couple of years, I know that being prepared is a relatively easy thing to do, even in the city. Per Mr. B's advice many moons ago, I got a 'hurricane kit' that contained food, water, emergency blankets, etc., PLUS a toilet (the bucket all of the food and such came in, also came with a toilet seat and disposable bags ). I also had a second, larger, kit in my car, which was full of gas at all times.
To supplement the apartment kit, I always had 6-10 gallons of drinking water on hand (lined up along the galley kitchen wall), cans and pouches of tuna and other foods that didn't require any heat (thanks to the Trader Joes down the street), BUT I also had a camp stove and a couple of small bottles of propane, plus a BUNCH of jar candles. I also had three months of cat food on hand at all times (just easier to buy it that way) and then I wouldn't have to worry about the cats killing me in my sleep. Was it a lot of fun schlepping all of that water, food, and cat food up to the fourth floor (yes folks, a fourth floor walk up)?? No, it wasn't, but I thought it was important enough to do.
All in all, I could have barricaded myself in (80 boxes of books plus shelving is pretty good for covering doors and windows) and have been good for at least two solid weeks and could stretch to three if I had to without leaving my apartment. Those things didn't take up a lot of space, even in a small urban apartment, didn't take a lot of money, and it gave me peace of mind.
7 months ago