Anyone trying to get into the US without a passport nowadays is a bloody idiot. The border guards are empowered to act on their own recognizance. They can detain you for hours. Take whatever ID you can and always tell the truth. As for racial profiling, the good agents don't do this (wouldn't have helped with Timothy McVeigh.....). However, I've seen many occasions of people of asian origin being pulled out the line for extra attention. Makes me sick. You can bet every non-Caucasian carries a passport - they've been through it for years.
If you are a landed immigrant, you also HAVE to have a Permanent Resident card to be allowed back into Canada by air (you can still walk over.....). If you are a citizen, you need proff of citizenship (such as a citizenship card, birth certificate or.... passport). If you travel on a foreign passport but are a Canadian citizen you need to carry your citizenship card.
Remarkably, you do not, legally, have to show photo-ID when travelleing by air with Canada. Most airlines demand photo-ID but it is not a statutary requirement. Moreover, in La Belle Provence, it is illegal to ask for Provincial identification (such as a driving licence) unless you are a government agency. Of course, don't try this at home or you'll be sitting in the departures hall.....
And for those of you with expired or no passports, be warned. There is a 6-10 week wait on passports and this gets worse in the run-up to Summer. Moreover, the number of rejected applications is now significant due to the many extra details and checks (such as submitting a photograph with any shadow, facial expression or head-covering).
Finally, the security guards are just doing their job. Make it easy for them. They are there to provide you with better safety. A week ago I was behind a complete idiot at Pearson. He was a contractor with a bag of tools (hammers, chisels, knives, box-cutters). He wanted to duck around the detectors and cussed the guards for making him take off his steel capped boots and tool belt.