Initially, communication could be done with a loud-speaker, to round up survivors, next you could switch to ham and CB radios to talk to people in your city and surrounding areas, after that, you might be able to re-purpose some power lines for telegraph or other wired communications; this could provide you with inter-city abilities.

Of course, if it’s something that wipes out our capacity for using electrical power easily, we could always fall back to smoke signals and reflected light, but I suspect that semaphore (set up in line-of-sight stations) would provide the best chances for long distance communications.

I say that now but all I can remember is dit, dit-dah, dah…dah-dah, dit. Throwback from Johnny B days (radio disc jockey).

When you get your license they give you instructions on what to do in case of emergency, as one of the answers said.

Pretending this emergency has already happened, this is what I remember, without looking anything up on the ‘net, so it could be partially wrong:

Regarding CB, that is simplex, i.e., radio to radio, and depends on how much power you have; so if you’re say, 50 miles from anywhere and the nearest person with a CB radio is 100 miles, I don’t think they will pick up your signal. HAM radios use repeaters, antennas on top of tall buildings, to carry their signal further. Which is why I could sit in my car in Chicagoland traffic and bitch to someone downtown about how bad the traffic was, whereas, out in the sticks, I was pretty limited unless I had a superior base station with lots of power. I don’t know if a repeater will work without power.

For listening to emergency broadcasts, I’d get a radio powered by a hand crank. For communicating, I’d go to a local school because I think that’s a likely gathering place due to the gyms and auditoriums. Communication via radio would be limited to those with generators, solar power, etc. Since most gas pumps don’t work without electricity, it would have to be conserved. Which leaves us with the Pony Express or bicycle messenger service.

I still like the original question, though; it followed me home, and I want to keep it. So have at!