Thus there was initiated by La Salle a dispute over the character of the water communication from Lake Michigan to the Mississippi by way of the Chicago Portage which has been revived in our own day, and in the decision of which property interests to the value of hundreds of thousands of dollars are involved.[12] Of the essential correctness of La Salle's description there can be no question. Considering its early date and the many cares with which the mind of the busy explorer was burdened, it constitutes a significant testimonial to his ability and powers of observation. It may well be doubted whether any later writer has improved upon--if, indeed, any has equaled--La Salle's description of the Chicago-Des Plaines route. From its perusal may be gathered the clue to the fundamental defect in the descriptions of the Chicago Portage which modern historians have given us. Overlooking the fact that the Des Plaines River was subject to fluctuation to an unusual degree, they err in assuming that the portage ceased when the Des Plaines was reached. The portage was the carriage which must be made between the two water systems. Hulbert is quite right in saying, as he does, that none of the western portages varied more in length than did this one.[13] In fact his words possess far more significance than the writer himself attaches to them; for the length of the carriage that must be made at Chicago varied from nothing at all to fifty miles or, at times, to even twice this distance. At times there was an actual union of the waters flowing into Lake Michigan with those entering the Illinois River, permitting the uninterrupted passage of boats from the one system to the other. At other times the portage which must be made extended from the south branch of the Chicago to the mouth of the Vermilion River, some fifty miles below the mouth of the Des Plaines. [Footnote 12: _The United States of America vs. The Economy Light and Power Company._ The evidence taken in this case constitutes by far the most exhaustive study of the character and historical use of the Chicago Portage that has ever been made.] [Footnote 13: Hulbert, _Portage Paths_, 181.]