The Northern Nevada 4A Region is a part of the Nevada Interscholastic Activities Association, governing the northern half of Nevada for high school athletics. The Northern 4A league is the large-school level, which has schools with enrollments of 1,200 and higher. The region is split into two leagues. The High Desert League and the Sierra League. Both leagues are divided by proximity with the High Desert encompassing the schools north of Mill Street in Reno, while the schools in the Sierra League are south of Mill Street.