EXPLANATION OF NAVIGATION CHARTS

1. The lateral scale of river charts is distorted. Mileage line only is drawn to scale. Sailing line is distorted.

2. Mileage is measured along the middle of the river at low water and on the channel side of islands and bars. Mileages are indicated on the charts for each

mile, and every fifth mile is numbered.

3. The zero of mileage is the Point Bridge, Pittsburgh, Pa.

4. Figures in parentheses following the name of a town give its population according to the census of 1930.

5. For the purpose of coordination, match lines with their respective mileages are shown at the top and bottom of each navigation chart.

6. Aids to navigation are designated by numbers which correspond to their mileages (to the nearest tenth of a mile), below the Point Bridge at Pittsburgh, Pa. 7. Locations of aids to navigation are changed from time to time. The type of aid may also be changed; for example, a daymark may be replaced by a flashing light. The latest information concerning aids to navigation on the Ohio River may be obtained from the Superintendent of Lighthouses, St. Louis, Mo.

8. Air navigation aids: All locks are marked by large figures placed on buildings so as to be seen from above.

1/2 O

I

Miles above mouth

Chart No. 1

Miles below

Right or left of Pittschannel burgh

977.4

977. 2

976.8

976. 3

976. 1

975.9

975.9

975.8

975.4

975. 4

975. 3

974.9

974.8

974.8

GAGE, EMSWORTH DAM (see p. 323).

PITTSBURGH, County Seat of Allegheny County, Pa. (669,817):
Industries: Manufacture of iron and steel; extensive banking and mer-
chandising; and a large variety of other industries.

Railroads: Baltimore & Ohio; Pennsylvania; Pittsburgh & Lake Erie;
Pittsburgh & West Virginia.

POINT BRIDGE.

Clearances: Horizontal 646 feet; available 646 feet. Vertical (mid 300 feet)
67.3 feet above level pool; 38.2 feet above 1907 high water.

SUBMARINE CABLE CROSSINGS (5).

0.0

027778

0

1

Clearances: Horizontal 755 feet; available 755 feet, Vertical (mid 300 feet);
72.3 feet above level pool; 44.2 feet above 1907 high water.

Clearances: Horizontal 508 feet; available 508 feet. Vertical 74.9 feet above
level pool; 48.9 feet above 1907 high water.

MCKEES ROCKS, Allegheny County, Pa. (18,116). (On back channel).
Railroads: Pittsburgh & Lake Erie.

L

2.9

MCKEES ROCKS HIGHWAY BRIDGE (see p. 226)

Clearances: Horizontal 750 feet; available 750 feet. Vertical (mid 300 feet)
111.7 feet above level pool; 87.1 feet above 1907 high water.

SUBMARINE PIPE CROSSING..

JACK RUN.

BELLEVUE, Allegheny County, Pa. (10,252). Railroad: Pennsylvania....
DAVIS LOCK WALL LIGHT

NEVILLE ISLAND (head)..

DAVIS ISLAND (foot).

SUBMARINE PIPE CROSSING.

AVALON, Allegheny County, Pa. (5,940). Railroad: Pennsylvania..
SUBMARINE PIPE CROSSING.

SPRUCE RUN.

BEN AVON, Allegheny County, Pa. (2,472). Railroad: Pennsylvania.
EMSWORTH, Allegheny County, Pa. (2,165). Railroad: Pennsylvania...
EMSWORTH LOCKS and DAM (see p. 168). (For regulations see p. 15)--
Locks on right bank. Main lock chamber 110 by 600 feet. Auxiliary lock
chamber 56 by 360 feet. No navigable pass.

3.3

6.8

974. 1

973. 6

CLIFTON, Allegheny County, Pa. (300). Railroad: Pennsylvania..
SUBMARINE PIPE CROSSING.

973. 4

DIXMONT, Allegheny County, Pa. Railroad: Pennsylvania.

GLENFIELD, Allegheny County, Pa. (950). Railroad: Pennsylvania..
NEVILLE ISLAND (foot).

8.6

9.9

HAYSVILLE, Allegheny County, Pa. (200). Railroad: Pennsylvania-
SUBMARINE CABLE CROSSING.

R

-10.2

10. 2 10.7

SEWICKLEY HIGHWAY BRIDGE (see p. 227).

Clearances: Horizontal 724 feet; available 724 feet. Vertical (mid 500 feet)
73.4 feet above level pool; 47.5 feet above 1907 high water.

STOOPS FERRY, Allegheny County, Pa.

Railroad: Pittsburgh & Lake Erie.

NARROWS RUN.