I drove the same car with the same content two days in a row from Mexico to the US via the same border crossing and the same lane (Sentri, as I have a Global Entry card). I was sent to secondary each time: the first time I was asked to be more thorough in my declarations for my future entries (otherwise my global entry card would be revoked), and the second time I was asked not to use the Sentri lanes if my car has too much stuff in it (otherwise my global entry card would be revoked).
I had never heard of such a limitation but I'm unfamiliar with the land border. Is there a limit on how full of items a car is to be allowed to drive from Mexico to the United States using the Sentri lanes, and if so, what's the limit? The inspectors from my first invitation to the secondary weren't at all bothered my numerous belongings, just the fact I hadn't declared them, so I am confused. I was driving a regular sedan with a full trunk and a few items in the back seat.
Global Entry card holders must follow all program rules for SENTRI when using this card at southern land ports of entry. For more information on SENTRI, please go to www.sentri.gov"
so maybe the info is on http://www.sentri.gov or https://www.sentri.gov? which is 404. I see on https://web.archive.org/web/20111201000000*/https://www.sentri.gov it used to point to http://www.cbp.gov/xp/cgov/travel/trusted_traveler/sentri/ which is 404 too. I'm guessing https://www.cbp.gov/travel/trusted-traveler-programs/sentri/ is the new page, but no info there.