High school 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, but its popularity is declining. Between 2009 and 2019, participation in high school football has declined by 9%. High school football began in the late 19th century, concurrent with the start of many college football programs. In the late 19th and early 20th centuries, many college and high school teams played against one another. Today, the oldest high school football rivalry dates back to 1875 in Connecticut, between the Norwich Free Academy Wildcats and the New London High School Whalers. High school football traditions such as pep rallies, marching bands, mascots, and homecomings are mirrored from college football. No true minor league farm organizations exist in American football. Therefore, high school football is generally considered to be the third tier of American football in the United States, behind professional and college competition. It is the first level of play in which a player will accumulate statistics, which will determine his chances of competing at the college level, and ultimately the professional level if he is talented enough. In the 2000s and beyond, there has been growing concern about safety and long-term brain health, both regarding the occasional concussion as well as the steady diet of lesser hits to the head.