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DEPOSITED BY THE
Notes and legend..
Charts, St. Croix River, mouth to Stillwater, Minn.
THE MIDDLE AND UPPER MISSISSIPPI RIVER
Mississippi River rises in the vicinity of Lake Itasca in central Minnesota and flows in a general southerly direction about 2,450 miles (measured along the natural channel) to the Gulf of Mexico. The section described in detail in this publication extends from the mouth of Ohio River near Cairo, Ill., to Minneapolis, Minn. The section between the Ohio River and the Missouri River (195.0 miles) is referred to as the Middle Mississippi River, while the section above the Missouri River is known as the Upper Mississippi River. The river is improved for barge navigation below the lower Northern Pacific Railway bridge at Minneapolis (853.0 miles above Ohio River), and extension of the improvement to surmount the Falls of St. Anthony and extend through navigation to the Soo Line Railway bridge (857.6 miles above Ohio River) has been authorized by Congress. Between Minneapolis and Alton, Ill. (202.9 miles above Ohio River) the navigation improvement is by means of locks and dams. Below Alton the improvement is made by channel dredging and open-river regulating works.
Mileages are measured along the centerline of the 1931 steamboat channel, and are stated in terms of miles above the Ohio River, the zero of the mileage system being the intersection of the thalwegs of the Ohio and Mississippi Rivers. Attention is invited to the fact that the mileage systems used in navigation charts of the Ohio and Lower Mississippi Rivers have slightly different origins, the former opposite Cairo Point and the latter at Cairo gauge, about 1 and 2 miles, respectively (along the Ohio River channel), above the intersection of thalwegs. For the convenience of those who prefer to use miles from Minneapolis a column of mileages measured from the lower Northern Pacific Railway bridge at Minneapolis is also shown.
PHYSICAL CHARACTERISTICS The more important physical characteristics of the Mississippi River are outlined in the following tables: