[2] Greenfield Township is located in the southwestern corner of Blair County.

Interstate 99 passes to the east of Claysburg along the side of Dunning Mountain, with access from Exit 15 near the southern edge of the township.

Other communities in the township include Ski Gap, Klahr, Friesville, Cotton Town, and Sproul.

According to the United States Census Bureau, the township has a total area of 36.3 square miles (93.9 km2), all land.

[3] A portion of the Pennsylvania State Game Lands Number 26 is located in the western portion of the township, and three small parcels of Game Lands Number 41 are located in the southwestern corner of the township.