Here's a simple but effective hack that could save your day. And your life.
If you're male: Before crossing into the US either by driving or any other form of transportation, SHAVE.
If you're white but have any kind of tan, SHAVE TWICE.
I got totally racially profiled on the way into the US today at the Rainbow Bridge in Niagara Falls and held up for about 30 minutes AFTER making it past the border officer. I flipped the coin and left home with about 1.5 weeks worth of scruff on my face against my better judgement, but I was in a hurry. Seeing as I'm originally from Western Europe, I have a naturally olive complexion and always get an envy-inspiring tan, even without trying. I guess these two things are a perfect storm, a magic cocktail that sets US border guards hearts fluttering.
And yes, I do cross into the US quite regularly, at least once every two months - the guys at the border scanning my passport know this. They asked all kinds of questions, some which they may have asked before, but many they've never asked. Also asked to see the registration papers for my car - which I've never been asked for ever. I travel with a Canadian passport and they may sometimes ask what nationality I am (duh!) but this time they also asked if I was born in Canada, then where I was born, then when I moved to Canada.
I would have loved to ask as I was leaving, "so, it was the beard right?" but I didn't dare - the last thing I wanted was to be delayed further or turned around.
So, SHAVE before going to the US.