Route 204 is a finite two-lane east–west highway on the south shore of the Saint Lawrence River in Quebec. It is one of the longest secondary highways in the province. Its eastern terminus is in Saint-Jean-Port-Joli at the junction of Route 132 and the western terminus is in Lac-Mégantic at the junction of Route 161. Although it is numbered as an east–west highway, the road follows a north–south course from Saint-Jean-Port-Joli to Saint-Pamphile, where it then follows a mostly southwest–northeast course until Saint-Georges, where after crossing the Chaudière River, follows it in a north–south course until the source of the Chaudiere in Megantic Lake, in Lac-Mégantic.