Here [is a picture] of the school bus my kids ride each morning.
School Districts 47 and 155 are the elementary and high schools, respectively, in Crystal Lake, Illinois.
As far as I’ve seen, none of the other buses have the apostrophe. I’ve seen at least one that has a space between the t and s, indicating an apostrophe once was there. But I think this may be the only bus that (still) has one.