Trois-Rivières, Qué, City, pop 46 264 (2001c), 48 419 (1996c), 49 426 (1991c), 77.83 km2, inc 1857, the regional capital of Québec's Mauricie region, is located on the west shore of the mouth of RIVIÈRE SAINT-MAURICE, midway between Québec City and Montréal. Its name derives from the 3-armed delta formed by the river's islands at its mouth.