It is located in Cumberland County and runs from Amherst at Trunk 6 to Streets Ridge at Route 368.

Heading east from the Town of Amherst the route is a two-lane collector highway with a posted speed limit of 80 km/h.

From Oxford it continues heading due east with a posted speed limit of 80 km/h until its terminus at Route 368.

Route 204 has been around unofficially for many decades and for many years was the main road between Truro and Amherst.

Before the 1960s, the section of Route 204 from Oxford to Streets Ridge was designated as Trunk 4.