Coastline of the U.S.A.: General Coastline, Tidal Shoreline, and Lengths of the Great Lakes ShorelinesEntry ID: CGS_NCD_COASTLINE
Abstract: GENERAL COASTLINE figures are lengths of general outline of the
seacoast. Measurements were made with a unit measure of 30
minutes of latitude on charts as near the scale of 1:1,200,000 as
possible. Coastline of sounds and bays is included to a point
where they narrow to width of unit measure, and the distance
across at such point is included. Most of the general coastline
figures are the same ... as those published in the First (1915)
Edition, but all were remeasured in 1948. The coastline of
Alaska was again remeasured in 1961, and again the 6,640-mile
figure of 1915 was retained. The principal change in the 1961
edition is the increase of Florida coastline from 1,1197 to
1,1350 miles; this was checked and re-checked and reflects a new
approach to measurement of the Florida Keys.
TIDAL SHORELINE figures were measured in 1939-40 with a recording
instrument on the largest-scale charts and maps then available.
Shoreline of outer coast, offshore islands, sounds, bays, rivers,
and creeks is included to the head of tidewater or to a point
where tidal waters narrow to a width of 100 feet.
LENGTHS OF GREAT LAKES SHORELINES AND CONNECTING RIVERS,
INCLUDING ISLANDS. These shoreline lengths were measured in 1970
by the International Coordinating Committee on Great Lakes Basic
Hydraulic and Hydrologic Data. A precision instrument called a
Map and Plan Measure, designed especially to determine the
lengths of broken or irregular lines, was used on topographic
maps and navigation charts. The scale of the maps was mainly
1:50,000 with a few larger scale maps. The scale of the charts
varied from 1:30,000 to 1:120,000.
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Creation and Review Dates
Last DIF Revision Date: 2005-08-09