Marathon Sponsor
Throughout the course of a marathon there are people that are standing along the course with waters, sports drinks or towels. Often times there is some sort of medical aide on call as well for all of the participants. These things come at a price.
Having sponsors at a marathon are very important and some people may not even be able to participate without having a sponsor. There is usually an entry fee for the participant to be in either the marathon or the half marathon. Some participants may want to compete but do not have the funds to cover the fees. A sponsor would then cover the fee for the participant and in exchange the participant may wear a t-shirt or hat with that sponsors logo.
Local businesses may even sponsor the marathon itself. The money that is given to the marathon goes towards operating costs. Most foundations that have marathons are non-profit organizations so they do not have a substantial amount of money to throw around for events.