I have some vague recollection of a person in my work place wearing orange for St. Patrick's Day because she was Irish/Protestant. But As Bill said, from my experience, it seems that that custom nowhere near as well known and practiced as wearing green for St. Patrick's Day.

I don't think that most Americans associate green with Catholicism, just with being Irish. And during that day, [supposedly] anyone can wear green even if they aren't Irish. However, it has been my experience that Black people get teased [in a friendly manner] if we wear green on that day. Though it's not the subject of this thread, I wonder if anyone has seen Asians, and people from the Middle East, and other people of color wearing green for St. Patrick's Day? I wonder if they also are teased about that...