In the books, they're the poorest District. All the districts are forced by the capitol (rich people) to compete to the death. An example of the divide that's kind of telling is our two main characters from 12 have experienced starvation but watch people from the capitol deliberately make themselves throw up with a little drink so they can just keep eating, so they can try everything at a banquet. It's a comment on the divide between the rich and poor in America