Route 173 follows the Chaudière River for most of its course, from Saint-Georges, down to Scott, where the route takes a more northeastern route towards Lévis, crossing the Etchemin River in the municipality of Saint-Henri-de-Lévis.
Route 173 traces most of its path along the Chaudière River, from Saint-Georges to Scott. From there, it takes a more northeastern route towards Lévis, crossing the Etchemin River in the municipality of Saint-Henri-de-Lévis.