According to the United States Census Bureau, the CDP covers an area of 2.1 square miles (5.4 km2), 96.44% of it land and 3.56% of it water.

There were 140 housing units at an average density of 66.7 per square mile (25.8/km2), of which 81 (87.1%) were owner-occupied, and 12 (12.9%) were occupied by renters.

[23] Federally, Cassel is in California's 1st congressional district, represented by Republican Doug LaMalfa.

[24] The Pacific Crest National Scenic Trail passes East of Cassel.

Just north of the town is the site of Packway Materials who have repurposed broken construction equipment into sculpture.