Lake Superior, the uppermost of the great border lakes of the United States and Canada, and the largest body of fresh water on the globe. It is included between lat. 46° 30' and 49° X., and Ion. 84° 50' and 92° 10' W.; greatest length from E. to W. 360 m.; greatest breadth, across its central portion, 140 m.; area, 32,000 sq. m. Its length of coast is about 1,500 m., its mean depth about 1,000 ft., and the level of its surface above the sea about 630 ft. The boundary line between Canada and the United States passes from Lake Huron up the St. Mary's river, the outlet of Lake Superior, through the centre of the lower half of this lake, to the mouth of Pigeon river on the N. shore, between Isle Royale and the Canadian coast. This island was allowed to fall on the American side of the boundary in compensation for one of the islands at the mouth of the St. Mary's river. The S. coast of the lake from the outlet to Montreal river belongs to the upper peninsula of Michigan. From this river to the river St, Louis the coast belongs to Wisconsin, and thence round to Pigeon river to Minnesota. Toward each extremity the lake contracts in width, and at the lower end terminates in a bay which falls into the outlet, the St. Mary's river, at the two opposite headlands of Gros Cap on the north and Point Iroquois on the south.

Thence to the mouth of the St. Mary's at Lake Huron is about 60 m. Numerous streams flow into Lake Superior, but none of large size. High lands in general lie near the coast, the long slopes from which are directed away from the lake and the short slopes toward it. The rapid fall prevents the navigation even by canoes of most of these streams, but provides excellent water power, which is almost everywhere available. The principal rivers are the St. Louis, which enters at the head of the lake; on the N. shore, the Pigeon, Kami-nistiquia, Black Sturgeon, Nipigon (the outlet of Nipigon lake), Pic, and Michipicoten; and on the S. shore, the Tequamenon, Sturgeon, Ontonagon, Montreal, and Bad. The coast of the lake is for the most part rocky, and on the 1ST. side is much indented by deep bays surrounded with high rocky cliffs, back of which the country soon rises in bleak and dreary mountains. Numerous islands are scattered about this portion of the coast, many rising precipitously to great heights directly up from the deep water. Some present castellated walls of basalt, and some rise in granitic peaks to various elevations up to 1,300 ft. above the lake.

Nowhere upon the inland waters of North America is the scenery so bold and grand as on the N. shore of Lake Superior. The irregularities of the coast with the general depth of water here afford numerous good harbors, which however in this unfrequented region are as yet of little service, while on the opposite coast such places of refuge are much wanted. The determination of the coast lines by the wearing action of the waters upon rocks of different degrees of hardness is remarkably exemplified everywhere along the shores of Lake Superior, particularly in the precipitous walls of red sandstone on the S. coast, famous in all the earlier accounts of the lake as the "Pictured Rocks." They stand opposite the greatest width of the lake and exposed to the greatest force of the heavy storms from the north. The effect of the waves upon them is not only seen in their irregular shapes, but the sand derived from their disintegration is swept down the coast below and raised by the winds into long lines of sandy cliffs. At the place called the Grand Sablo these are from 100 to 300 ft. high, and the region around consists of hills of drifting sand. The principal bays are Thunder, Black, and Nipigon on the north, Tequamenon at the outlet, Keweenaw on the south, and Fond du Lac at the head.

The largest islands are Isle Royale and Michipico-ten. The most important places on the shores of the lake are Marquette, Mich., and Duluth, Minn. There are many varieties of excellent fish, the most valuable being white fish, sturgeon, and trout. - For the mineral productions of the Lake Superior region, see Copper Mixes, vol. v., p. 323; Iron Ores, vol. ix., p. 407; Michigan, vol. xi., p. 497; Ontario, vol. xii., p. 635; and Silver, vol. xv., p. 57.