While INS/Customs/BP might go ahead and let people cross it should be pointed out,(link below)
The Western Hemisphere Travel Initiative (WHTI) requires U.S. and Canadian travelers to present a passport or other document that denotes identity and citizenship when entering the U.S. It is a result of the Intelligence Reform and Terrorism Prevention Act of 2004 (IRTPA).
The goal of WHTI is to facilitate entry for U.S. citizens and legitimate foreign visitors, while strengthening U.S. border security. Standard documents will enable the Department of Homeland Security to quickly and reliably identify a traveler.
WHTI went into effect June 1, 2009 for land and sea travel into the U.S. WHTI document requirements for air travel went into effect in 2007.
Now of course they can let you pass,,,but Custom/INS can also have an attitude at times as well.
While those of us close to the border are well aware of the law, someone not close to the border might not be. Because of that, I would prefer to let them know what the actually law is and not what they might be allowing at the time. After all it would pretty much suck, and not in a good way, to be detained at the border for 2+ hours because all of a sudden, they decided to enforce the law or you get the agent in a bad mood. I think all of us living close to the border have either heard someone's bad experience or have had a story ourselves in crossing back. BTW your NBA and traveling was a good one!