Many (most?) US cities lack provisions for bicycles like dedicated lanes, etc., though I don't know about Durham specifically. The situation is worse outside major cities, too.

Another thing I've noticed is that many US drivers don't know how to, or are uncomfortable dealing with, driving near cyclists. Sometimes they're just careless and hostile toward cyclists - in one instance, I saw a driver attempt to drive a person on bike off the road with his car in an apparent fit of rage.

Where I live, there are some bicycle-friendly roads, but if you need to commute by bicycle you are probably going to get some road segments with absolutely no paved shoulder. So the smart thing to do then is to have a mirror, and if a car is coming up behind you and another one is oncoming (two-lane road), your best bet is to hit the gravel.

Also, there are some stretches of road where bicycle clubs seem to frequent. What they do is get a large pack of people, and end up blocking traffic on a 5-mile stretch (they purposely take up the whole lane, probably safer that way I guess, and when there is a bottleneck instead of moving right they take up both lanes). This ends up instilling a large amount of hostility in drivers, so when they see a loan bicycle they tend to be very aggressive (I've had water balloons, even beer bottles thrown at me before, even though I was far right of the white line).