How stringent is the border crossing from Tijuana Mexico to San Diego?

I'm asking as a caucasian who doesn't appear at all Latin American

As a white guy from San Diego, I've crossed back into the US from Tijuana countless times without incident. If you're making the crossing by foot, you'll stand in a line, the INS agent will ask you your country of origin, occasionally they'll ask a couple questions about your visit, and you're all set. The only hitch is if you have something that you shouldn't. One buddy of mine had some roids stashed in his sock, and he was detained for quite some time. Another group got into trouble while dragging their drunk-to-unconciousness buddy back across. That's not to say they'll catch you every time, my amigo had had several successful roid shopping trips before the incident, and I grew up playing with imported fireworks. But essentially, if you've got nothing to hide, you've got nothing to worry about. I've never been hassled.

If you're coming back via car, the interview process lasts a little longer... where did you go, how long, what did you do, bringing anything back across? Had the agent go through the backseat once and asked about a couple things. By and large though, the agents I've talked to are actually pretty nice. I think the whole point of the conversation is to see if you're unnecessarily nervous or shifty, in which case they may have you pop the trunk or send you in for a Secondary inspection of your car/person. But once again: if you've got nothing to hide, you've got nothing to worry about.

Your car will get walked past by drug dogs and looked under with mirrors on sticks. I wouldn't be surprised if you get looked at with something like a big x ray or something. Then there is the "random" searches. If you are trying to carry something across, it is easier to walk it through customs than drive. If you have ever had to come through customs at the airport, it is about like that.

You do need the correct ID ... and they will talk to you

I crossed the border less than a year ago and it was not at all stringent. We took the trolley down from San Diego, so we just did the walk-through border crossing each way. There was not really any security going into Tijuana. On the way back, we just had to pass through a turn style and show a border patrol officer our driver's license. I was with a group of girls and we only had our purses and a few small shopping bags. None of us look Latin American. He didn't even go through our belongings. All in all, it took us less than 5 minutes to cross the border.

However, I do believe that they are currently tightening security. It may be different now.