circuit for student-run teams and colleges that choose not to compete at the varsity level. In addition to this, 10 colleges field teams in the Collegiate Sprint Football League, a league in which all players must weigh no more than in order to be eligible to play; four of those teams are long-established sprint teams that co-exist alongside their NCAA counterparts (two from the Ivy League and two military academies), while six teams that have been added since the CSFL began an ongoing expansion in 2008 either never had a varsity squad (one recent addition, 2015 expansion team Chestnut Hill College, was an all-women's school that did not even admit men until 2003) or downgraded from an NCAA team to a sprint team. High school Most American high schools field football teams. High school football is popular; top schools regularly fill stadiums holding over 10,000 fans, and can afford artificial playing surfaces. High school teams generally play only against other teams from their state (notable exceptions include matchups between nearby schools located on opposite sides of a state line and occasional matchups between two nationally ranked teams for television purposes). Still, some private Christian high schools play for national championships through organizations like the Federated Christian Athletic Association. Public high school football in most states, as is the case with other high school sports, is governed by the National Federation of State High School Associations (NFHS). For rural schools that do not have the student body to support a full football team, the NFHS sanctions nine-man football (most popular in the upper Midwest), six-man football (most commonly used in Texas, although previously more widely popular and undergoing a minor revival elsewhere), and eight-man football (which the most common reduced-man format in most other states). Adult Amateur Football / Semi-Pro Football Adult amateur football, also known as semi-pro football, is a level of American football. It is commonly known as "working man's" football, meaning the players have regular jobs and play football on the weekends. Though the players do not get paid, the leagues and the games are run in a somewhat professional manner. For most leagues, it is against the rules to pay its players to play. The rules of the game are usually a hybrid of NFL and NCAA rules. There are several different leagues playing in the United States: The North American Football League (NAFL) was an adult