Greencastle-Antrim School District (GASD) is a K-12 public education school system located in the Cumberland Valley within south-central Pennsylvania. GASD borders Maryland and is bisected by Interstate 81. It lies south of Chambersburg in Franklin County and covers 72 square miles including the Greencastle Borough and Antrim Township. GASD has a history of providing quality educational experiences for approximately 3,100 students.