nanowrimo_lj | Power Outages

I don't know how to go about researching this without getting on a terrorist watch list, haha.

I'm trying to write a mass power outage into my story. But I need to know:

Would outages happen on a city by city basis, or could something happen to make an entire state lose electricity?
If said outage were to happen, what could cause it?
I'm sure this depends on the cause of the outage, but worst case scenario, how long would people be without power?
What types of buildings have backup generators to insure they will still have power in case of emergency? Hospitals and jails, I'm sure, but what else? Would a bank have a backup generator to keep the alarms going and the safe locked if the power's out?

The story is taking place in the USA. I Googled "National Grid USA" and found that there's a company by that name that manages just a few states. So am I correct in assuming there is no large-scale utility authority that manages the entire country? That's fine, it just makes my job harder, because I will have to write in several smaller outages instead of just POOFing everyone's electricity, haha.