Marathon Independent School District is a school district based in Marathon, a census-designated place in Brewster County, Texas, United States.

Typically due to its isolation, Marathon generally has the lowest high school enrollment in the state.

[4] As of 2007, the Texas State Energy Conservation Office awards Marathon ISD money due to the colonias served by the district.

[5] In 2009, the school district was rated "recognized" by the Texas Education Agency.

[6] The Marathon Mustangs compete in the following sports - [7] (Both teams were undefeated).