Didn’t ask about Halloween. I asked about trick or treat. Many places have trick or treat on days other than Halloween; it varies every year.

https://www.nytimes.com/2010/10/29/us/29halloween.html

Maybe in Baltimore. Not true everywhere - one example from last year: https://www.charlestonwv.gov/news-items/thu-09232021-1044/trick-or-treat-2021. It’s very common in other places for trick or treat to not be on October 31.

Thanks all! I did try Google but gave up the ghost after page 4.