102 
THE ILLINOIS RIVER SYSTEM. 
The length of the [linois from its mouth to the place of its 
formation by the junction of the Des Plaines and the Kankakee 
is about 270 miles,* and if to this be added the length of the 
Kankakee, the longest tributary, the total amounts to 505 miles. 
This is about the length of the Seine, of the Rhone, and of the 
Oder; of the Des Moines and of the Sacramento ; it is about one 
half the length of the Rhine and of the Yellowstone, one third 
that of the Danube, and over twice that of the Thames and the 
Tiber. The distance, in a direct line, from the junction of the 
Des Plaines and the Kankakee to the mouth of the Illinois is 
214 miles. The increase in length due to the windings of the 
stream is thus 61 miles or 28%, and the ratio of the development 
of the stream is1: 1.28. From the mouth of the main stream to 
the head waters of the Kankakee, in a direct line, is 315 miles. 
Upon this basis the increase due to windings is 190 miles or 
60%, and the ratio of development is 1: 1.6. The ratio of de- 
velopment of the Connecticut River is 1 : 1.2, and that of the 
Mississippi, as a whole, is 1 : 1.5, while from the mouth of the 
Ohio to the Gulf itis 1: 2.0. Itis evident that the main stream 
of the Illinois has an exceptionally direct course, though the 
channel of the Kankakee is not of this character. 
The area of the basin drained by the Illinois is approxi- 
mately 29,000 square miles. This is more than twice the area 
of the Hudson, and also of the Connecticut, and is comparable 
with that of the Susquehanna, of the Potomac, of the Po, of the 
Duero, of the Rhone, and of the Loire. It constitutes less than 
one forty-third of the entire Mississippi basin. According to 
Greenleaf (’85) the drainage basin of the Illinois comprises an 
area of 29,013 square miles, 24,726 of which he within the state, 
1,080 in Wisconsin, and 8,207 in Indiana. About three sevenths 
of the area of the whole state belong to the drainage basin of 
the Illinois. The following list of tributaries with their respect- 
ive areas is taken, with slight modification, from Cooley (’89). 
*The statement of the Standard Dictionary (p. 2172) that the length of the IIli- 
nois River is 350 miles is manifestly incorrect. 
