If you are in a large, congested city area like center city Philadelphia, that is a rarity. Where it does happen there is often a bike lane or the street is wide enough that it's not a problem. Also, more and more people are realizing that it makes no sense to speed up to the next red light. And you don't really have the problem of people flying past you and then turning into the strip mall or gas station right in front of you like you do when you ride somewhere like in developed S. Jersey. Riding in some big cities can be comfortable once you get the hang of it.

BTW...I have toured a fair amount in MT. The first year I rode there ('99) they had recently adopted speed limits again. Was just there again last year. I found the vast majority of drivers to be very courteous. And yes, outside of the cities and exurban sprawl (e.g., the Bitteroot Valley SE of Missoula) there ain't much traffic.

Did you know that every inch of Interstate Highway in MT is open to cyclists? Sometimes it's the only way to get between two points. I rode short stretches of I-90 a couple of times during a '11 tour there. It's wasn't as bad as you might imagine.