What could happen to a young boy walking the Michigan streets in the middle of the night during the 1930s?
I think the novel charts a number of possible threats to a boy in Bud's position at the time of the novel - he could have been attacked, robbed or beaten without too much worry. We need to remember what conditions were like during the Depression and the widescale poverty that made people desperate and commit desperate acts in order to gain food and shelter for themselves and their family. Bud himself displays enough suspicion to make us realise that the society in which he finds himself in seems to be based often on distrust and animosity.
Oh, lots of things! In general, think of it as the streets of today, combined with two other factors: the Great Depression and racism. The Great Depression left a lot of people desperate. They were hungry, starving even, and willing to do things that they wouldn't have done when they were well-fed.The racism is even worse. Racism was more extreme and more overt in America at that time, and the depression made it even worse. There were lynchings, and it would have been possible for a young boy to be killed just for his race alone.
Reading the part where Bud, Not Buddy had to hide in the bushes every time someone passed him is very sad. Not only was he at a disadvantage for his race, but his age. There were many runaways and orphans hiding from the law. The times were hard for these children all over. Foster parents were mean and money hungry. Their lives were no better in the foster home than the orphanage. Children were treated horribly and just like the adults were exposed to lynchings, corporal punishment, and injustice.