Colfax Township contains half of the village of Thompsonville, and the entire community of Nessen City According to the United States Census Bureau, the township has a total area of 35.9 square miles (93.0 km2), of which 35.6 square miles (92.3 km2) is land and 0.27 square miles (0.7 km2), or 0.72%, is water.

[3] Colfax Township forms the southeastern corner of Benzie County, forming a quadripoint with neighboring Grand Traverse, Manistee, and Wexford counties.

The Betsie River flows through the township, east to west, toward Lake Michigan.

As of the census[1] of 2000, there were 585 people, 224 households, and 170 families residing in the township.

20.5% of all households were made up of individuals, and 6.7% had someone living alone who was 65 years of age or older.