I put a bit of work into answering a picture based question based on details in the drawing, and it was deleted by a moderator with the comment Since this is not a serious attempt to answer the question, it has been removed.
Could Deusovi reconsider? If you have questions on the story illustrating the answer or interpreted something as mocking the community (I assure you it wasn't intentional), I'm happy to hash them out to fix everything up to standards. Having my contribution, which I thought made very good use of the details in the picture to solve the riddle, deleted has kind of bummed me out.
In it's full form:
I think Bob knew the bus was facing north because of
the direction of the bloody trail his fellow bus driver Alice left running towards Canada.
Allow me to explain:
Alice the after-school bus driver is a bit of a lush, which Bob is sure no one else knows about because of their notoriously secure correspondences. He's been on ride alongs with her during semiannual reviews and personally seen her swerve around underage pedestrians playing near the school. "She better be careful," Bob would say under his breath, "or she might catch a disciplinary action form one day."
When Bob got into the bus that morning, he was horrified to find
the body of a dead child unceremoniously stuffed into the first row, almost fully dressed in outdoor play gear, but with the head caved in and covered with black, frozen blood. "Of course," thought Bob, as he recalled the cracked headlight on the left side of the bus moments ago. And wasn't there something on that same tire? He couldn't remember, but vaguely thought he recognized red paint, which he now understood to be the tiny victim's blood.
In a flash, he remembered
almost tripping on something right before he boarded. A shoe. In his mind's eye, he could see it. One, child-sized, red shoe, perfectly matching the one on the corpse before him. It would perfectly cover the exposed, white sock on the other side. The streaks and markings of blood around the bus steps strongly suggested it was flung from the child's body during a turbulent ride to the bus park and subsequently kicked off during Alice's hasty escape...
Which Bob could plainly see at a glance, because as he slowly raised his head, facing the door he just entered, he looked past
that little red shoe and saw Alice's tracks, in the gray Michigan snow, extend straight through the parking lot, across the adjacent field, all the way to the Detroit river. Due east. Into Canada.
Therefore, Bob knew the bus must be facing north!