Asslmbow, a river of British North America, rising in lat. 51° 40' N. and about lon. 105° E., and joining the Red river of the North at Fort Garry, Manitoba, in lat. 49° 54' N. Its course is a distance of over 400 m. At a point 22 m. above Fort Garry it is 120 ft. wide, and has here in summer a mean depth of about 6 ft.; 140 m. from its mouth its breadth becomes 230 ft. and its mean depth over 8 ft.; at 280 m. its depth increases to over 11 ft. with a width of 135 ft. It receives in its course the waters of the Little Souris, Qu'appelle or Calling river, the Rapid river or the Little Saskatchewan, White Sand river, and Beaver creek. At its junction with the Little Souris, 140 m. from Fort Garry, the volume of water is 12,899,040 gallons an hour; while at Lane's Post, 118 m. lower down, this volume is diminished, Mr. Hind asserts, more than one half; a result which he attributes to evaporation. At Fort Ellice the secondary banks are 240 ft. high, forming an eroded valley nearly a mile and a half wide.

Parts of its course are bordered by inconsiderable forests of oak, ash, elm, maple, birch, poplar, and aspen.