Jamieson, Fausset and Brown on Numbers 26:55

55. the land shall be divided by lot--The appeal to the lot did not place the matter beyond the control of God; for it is at His disposal (Pr 16:33), and He has fixed to all the bounds of their habitation. The manner in which the lot was taken has not been recorded. But it is evident that the lot was cast for determining the section of the country in which each tribe should be located--not the quantity of their possessions. In other words, when the lot had decided that a particular tribe was to be settled in the north or the south, the east or the west, the extent of territory was allocated according to the rule (Nu 26:54).