MIDDLE AND UPPER MISSISSIPPI RIVER

NOTES

1. The lateral scale of river charts is distorted.

2. The channel line shown on the river charts indicates the location of the navigation channel in the fall of 1946.

3. The zero of mileage above the Ohio River is the intersection of the thalwegs of the Ohio and Mississippi Rivers near Cairo, Illinois. Mileages are indicated on the charts for each mile, and every fifth mile is numbered. The mileage does not represent distances measured along the present sailing line.

4. Shore lines as indicated on the navigation charts for that portion of
the river below Lock and Dam No. 26 at Alton, Illinois represent the
mean low water line; above Lock and Dam No. 26 the shore line is for
a full pool at dams and discharges which are equalled or exceeded 90%
of the time. Clearances above pool as given in the tables and on the
bridge sketches are based upon the same pool profile. The clearances
above high water for the table and sketches is based upon the
maximum stage of record.

5. Locations of Navigation Aids are changed from time to time. The
type of aid may also be changed; for example, a daymark may be re-
placed by a flashing light. The latest information concerning the aids
may be obtained from the Commander, Second Coast Guard District,
224 U. S. Custom House, 8th and Olive Streets, St. Louis 1, Mo.
6. Figures in parenthesis following the name of a town indicate its
population. Populations of towns of less than 100 are not given.