As green card holder, I crossed border in Detroit, MI over to Canadian side, just to do a 1 hour tour for fun, but coming back, the custom wasn't as quick, they asked me a bunch of questions like why I crossed the border an hour ago, who Detroit as I currently live in New Jersey, it seemed that there was some discrepancies (I could be wrong) that two officers had to look at the computer to finally let me go as the bu…
Did something similar in Montana, we just wanted to cross, take a picture and cross back - 5 minute trip. Got very similar treatment.