I am confused regarding what I am supposed to declare when driving from Mexico to the United States, as a US lawful permanent resident and French citizen.
https://www.smartertravel.com/customs-duty-free-guide/, which is for airlines (unsure whether the same applies to entries by land), states:
You’ve been out of the country on a much-deserved vacation. About an hour before your plane lands, the flight attendant hands you a U.S. Customs declaration form. Chances are you purchased a few souvenirs or gifts during your travels—so which ones do you have to declare? The answer: Every item you didn’t have with you when you originally left the United States.
what items must you declare when entering the United States? In essence, you have to declare any items you purchased and/or are carrying with you upon your return to the United States that you did not have when you left.
I assume that I must also declare any agricultural products and any presence of >10kUSD of cash, regardless of where they come from.
However, a US immigration officer told me during a secondary inspection when I was driving from Mexico to the United States that I should have declared items that I were already in my car when I entered Mexico from the US. When I asked him what specifically I should declare, he mentioned as example that I should have declared my clothes present in my car's trunk as well as my electronics. I was advised that my Global Entry privilege would be revoked if I do the mistake again.
Who's right? The websites or the US immigration officer? If the latter (=meaning that when entering the US from Mexico, I must declare items that I had in my car when I entered Mexico from the US), do I have to declare all items, or just a few types of items?