You have gotten excellent information regarding the official U.S. State Department requirements regarding needed identification for crossing the border. Now I'll give you some anecdotal experiences. As a frequent border crosser between the U.S. and Mexico I have never been asked by either the Customs agents nor the Immigration agents (both man the gates on the border) for the certified copy of my birth certificate. In fact, I've never carried one. Just last Saturday night a group of ten of us traveled to Tijuana for dinner. The only identification we carried was our driver's licenses.

In the 30+ years I've been crossing the San Diego-Tijuana border I've never been asked for identification while driving across, even after being pulled into secondary inspection. And when walking across I show my driver's license merely as a means of speeding the process along. For the few months following the attacks of Sept. 11th I always carried my passport but was never asked for it. The agents merely ask for your place of birth. Those times when I've been traveling with non-U.S. citizens the agents have always required to see correct documentation for these people, whether it be a passport or green card. As an interesting aside my various dogs have never been asked for their proper papers either (and they always carry their official Dept. of Agriculture paperwork)

However, whenever I travel beyond the immediate border vicinity of Baja California (such as into central Mexico) I always carry my passport. That holds true for all trips I take into Canada.

What does this mean for your brother's girlfriend? Nothing. It's merely an anecdote. But I'd suggest she get a passport so this problem doesn't come up in the future.

John in San Diego