Mad River (formerly Kuntz) is a census-designated place (CDP) in Trinity County, California.

Mad River has the last services on California State Route 36 until the Platina Store, 44 miles (71 km) away.

Its post office serves itself and the communities of Dinsmore (Humboldt County), and Van Duzen; both using 95552 as their ZIP code.

Myth has it that the leader of the party, in apparent anger with fellow companions over latitude positioning, coined the term when comparing the experience of the difficult exchange between his peers.

Most of the communities that encompass the former Mad River CCD are off main highways and at least 100 miles (160 km) from a major city.

The area code for most of the region is 707, because phone service comes from larger communities in Humboldt County, such as Bridgeville or Garberville.

According to the United States Census Bureau, the CCD has a total area of 155.6 square miles (403 km2) all land.

According to the United States Census Bureau, the CDP covers an area of 34.65 square miles (89.7 km2), all of it land.

[5] This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 85 °F (29 °C).

[9] Federally, Mad River is in California's 2nd congressional district, represented by Democrat Jared Huffman.