Exactly, in CLT (Charlotte) Canadians are lumped in with the other non-us citizens (excluding permanent residents of US who go with us citizens). If you are Canadian and you go into the US Citizen queue you will be made to go to the end of the of the foreigner queue after waiting to get to the front of the American citizen queue.

Every airport IS different and every agent IS different. So you really should ask when coming into passport control.