High school football, also known as prep football, is gridiron football played by high school teams in the United States and Canada. It ranks among the most popular interscholastic sports in both countries. It is the level of tackle football that is played before college football.

Rules

The National Federation of State High School Associations (NFHS) establishes the rules of high school American football in the United States. In Canada, high school is governed by Football Canada and most schools use Canadian football rules adapted for the high school game except in British Columbia, which uses the NFHS rules. Since the 2019 high school season, Texas is the only state that does not base its football rules on the NFHS rule set, instead using NCAA rules with certain exceptions shown below. Through the 2018 season, Massachusetts also based its rules on those of the NCAA, but it adopted NFHS rules in 2019. With their common ancestry, the NFHS rules of high school American football are largely similar to the college game, though with some important differences: At least one unique high school rule has been adopted by college football. In 1996, the overtime rules originally utilized by Kansas high school teams beginning in 1971 were adopted by the NCAA, although the NCAA has made five major modifications. Through the 2018 season, each possession started from the 25-yard line. Since 2021, this remains in force through the first two overtime procedures. In double overtime, teams must attempt a two-point conversion after a touchdown. Secondly, triple overtime & thereafter are two-point conversion attempts instead of possessions from the 25-yard line, and successful attempts are scored as conversions instead of touchdowns. Thirty-four states have a mercy rule that comes into play during one-sided games after a prescribed scoring margin is surpassed at halftime or any point thereafter. The type of mercy rule varies from state to state, with many using a "continuous clock" after the scoring margin is reached (wherein, except for specific situations, the clock keeps running on plays where the clock would normally stop). Other states end the game once the margin is reached or passed. For example, Texas uses a 45-point mercy rule (to stop the game) only in six-man football; for 11-man football there is no automatic stoppage but the coaches may mutually agree to use a continuous clock.

Demographics

High school football in the United States is played almost entirely by boys. Over the past decade, girls have made up less than half a percent of the players of American high school football. Eight states have high schools that sanction the non-contact alternative of flag football, but none sanction tackle football for girls, and a 2021 lawsuit in Utah that claimed the state violated Title IX laws by not sanctioning the sport was struck down. According to the New York Times, in 2006, 70% of high school football players were white and 20% were black. By 2018, those figures were 30% white and 40% black. , black youth are nearly three times more likely than white youth to play tackle football. In the 2010s, participation in high school football decreased in most states across the United States. Wisconsin saw the largest decrease, dropping by nearly a quarter from 2009 to 2019; only seven states saw an increased number of players. Its popularity decline is partly due to risk of injury, particularly concussions. According to The Washington Post, between 2009 and 2019, participation in high school football declined by 9.1%.

Safety and brain health concerns

Robert Cantu, a Professor of Neurology and Neurosurgery and Co-Founder of the CTE Center at the Boston University School of Medicine, believes that children under 14 should not play tackle football. Their brains are not fully developed, and myelin (nerve cell insulation) is at greater risk in shear when the brain is young. Myelination is completed at about 15 years of age. Children also have larger heads relative to their body size and weaker necks. Chronic traumatic encephalopathy (CTE) is caused by repeated brain trauma, such as concussions and blows to the head that do not produce concussions. It has been found in football players who had played for only a few years, including some who only played at the high school level. An NFL-funded study reported that high school football players suffered 11.2 concussions per 10,000 games or practices, nearly twice as many as college football players. According to 2017 study on brains of deceased gridiron football players, 99% of tested brains of NFL players, 88% of CFL players, 64% of semi-professional players, 91% of college football players, and 21% of high school football players had various stages of CTE. Other common injuries include injuries of legs, arms, and lower back.

The largest stadiums by capacity

Below are the largest high school American football stadiums by capacity. Stadiums with a capacity of at least 10,000 are included.