Allamuchy is located in Warren County along the Pequest River. The Musconetcong River forms the Township's southeastern border. Most of Allamuchy's 21 square miles are still forests and farms. The only substantial development is the Panther Valley community at the juncture of Interstate 80 and Route 517, a 1,200-home development of single-family homes, condominiums, and townhouses.