NOAA Medium Resolution Shoreline Documentation


Document Introduction/Navigating the Meta-Documents: This document contains the meta-information for the NOAA Medium Resolution Digital Vector Shoreline data product generated by the NOAA National Ocean Service Special Projects Office. It is divided into eight sections:

Click on the desired topic title for more information on that topic.

Caveats: Please Read This First!

Beta Release:

The data provided through this website has been through several levels of quality checking for the purpose of error detection and rectification. This is to insure that we deliver a product which is as free of error as is possible. However, in an effort to further improve the quality of the data, this release has been designated as beta. In doing this, you, the user, are encouraged to make us aware of any and all problems which you encounter with regard to the positional and physiological accuracy of the shoreline, and the associated descriptive attributes. Contact information is provided at the end of this document. Your cooperation and participation in this phase of the product release effort is greatly appreciated.

Thank you.

Implied Accuracy of the Supplied Information:

The data supplied here is a compilation of information collected from numerous current or pre-release National Ocean Service (NOS) Navigation Charts. In compiling this product we made no attempt to ascertain the congruency between the charted data and the real world. Our objective was to simply capture the representative coastline as provided to us via the NOS Chart. Every effort was made to capture the shoreline on these charts as faithfully as our skills and technology allowed, and there is every indication that we were successful to this end. However, in doing so, we automatically conveyed the character (all aspects, both good as well as bad) of that data to our digital product. A character which may or may not be in agreement with the real world. Because of this, the user is advised to exercise caution in making any assumptions about the fallibility, or infallibility, of the spatial information supplied here; especially when circumstances warrant a high degree of absolute positional accuracy.

Navigation Disclaimer:

PLEASE NOTE: This data is not to be used for navigation or navigation planning.


Introductory Information

Official Product Name:

NOAA Medium Resolution Digital Vector Shoreline.

Introduction/Brief Overview:

The NOAA Medium Resolution Digital Vector Shoreline is a high quality, GIS-Ready digital document containing the coastline of the contiguous United States of America. The shoreline was created from data captured (digitized from scanned images of the master separates of the NOS Charts) from hundreds of National Ocean Service Navigation Charts and spans some 75,000 nautical miles at an average map scale of approximately 1:70,000. The data set is designed for a broad target audience ranging from governmental agencies, universities and other research institutions, to the private sector, and students, as well as any other concern requiring a general purpose digital shoreline layer for GIS and cartographic projects.

Currency of Product:

Data sourced during compilation was the most up to date available at the time. Revision edition dates range from 1988 through 1992, depending on the revision cycle of the individual chart. Revision dates for the sources charts used in compilation are supplied as a part of the descriptive attribute data listings associated with each shoreline section.

Quality Assessment:

Spatial data was derived directly from National Ocean Service Navigation Charts. The NOS Chart Products meet or exceed National Map Accuracy standards (hard copy); the digital data supplied in this compilation should, when plotted at scale, meet or exceed these same cartographic standards.

Geographic Extent of the Products/Completeness:

Overall geographic extent of data (minimum bounding rectangle for entire data set):

Northwest Corner: Latitude 49.020 N, Longitude -124.762 W
Southeast Corner: Latitude 24.502 N Longitude -66.849 W

The image below identifies the locations of each sub-regional (shoreline section) file within the Medium Resolution Digital Vector Shoreline.

Sub-regional (shoreline sections) Map of Medium Resolution Digital Vector Shoreline

The four major regions comprising the digital shoreline are:

A series of data tables are available to aid in the correlation of NOAA nautical charts used in developing the digital shoreline sections. One table is a sorted list of all NOAA nautical charts used in developing the digital shoreline which identifies the shoreline section(s) containing the NOAA nautical charts. Tables listing section specific charts are also available from the list below.

Atlantic (East Coast) Section

EC80_01 -St Mary's Inlet Florida to Little River Inlet South Carolina.
-Little River Inlet South Carolina to Cape Henry Virginia.
-Chesapeake Bay.
-Chincoteague Inlet Virginia to Block Island Sound Rhode Island.
-Point Judith to St. Croix River.
-St Mary's River, Florida to Florida Bay (including the Florida Keys.)

Gulf of Mexico Section

GC80_01 -Padre Island TX to Bayou Choupique, LA
GC80_02 -Lake Calcasieu, LA to Atchafalaya Bay, LA
-Point Au Fer, LA to Barataria Pass, LA
-Grand Terre Island, LA to Gulfport, MS, incl. the Chandeleurs Islands.
-Biloxi River, MS to Chassahowitza Reefs, FL
-Chassahowitza Reefs, FL to Flamingo, FL

Pacific (West Coast) Section

WC80_01 -Semiahoo Bay, WA to Yaquina Head, OR
-Alsea Bay, OR to Point Sur, CA
-Point Sur, CA to U.S./Mexico Border

Great Lakes Section

GL80_01 -Lake Superior
-Lake Michigan incl. Lake Winnebago, WI.
-Lake Huron incl. North Channel, and Georgian Bay.
-Lake Erie incl. Detroit, St. Clair, and Niagara Rivers, and Lake St. Clair.
GL80_05 -Lake Ontario incl. St. Lawrence River to Ogdensburg, NY


Spatial Reference

Data Structure:

Vector; Arc-Node.


Data Structure Statistics:

Shoreline Section Arcs Vertices
EC80_01 4327 176380
EC80_02 3212 47510
EC80_03 3130 253842
EC80_04 3035 172121
EC80_05 840 176546
EC80_06 5852 191049
Atlantic (East Coast) Totals 23396 1117448
GC80_01 3628 127363
GC80_02 159 101624
GC80_03 556 161867
GC80_04 865 210622
GC80_05 705 123990
GC80_06 5509 175312
Gulf of Mexico Totals 24422 900778
WC80_01 468 107790
WC80_02 200 148127
WC80_03 468 28610
Pacific (West Coast) Totals 5136 284527
GL80_01 730 33824
GL80_02 818 43745
GL80_03 1753 53935
GL80_04 761 40760
GL80_05 334 21907
Great Lakes Totals 4396 194171
Overall 57350 2496924


Topologies Supported:

Arc. Arc spatial and descriptive attributes.


None; spherically referenced.

Average mapping scale:

1:69,556 (approximately 1:70,000).

Data set resolution is nominally of a map scale of 1:70,000. This is in keeping with original objectives for the project and the availability of NOS Charts at this scale. Actual resolution of the shoreline data does, however, vary locally, as a result of non-continuous coverage of the U. S. Coast at the targeted scale. Actual source chart scales range from 1:10,000 to 1:600,000, depending on the particular section of coastline in question. Most of the areas captured at non-target scales are quite small in extent, i.e., harbors, sections of rivers, channels and interior waterways with most charted scales at 1:40,000. Other areas could be assembled only at smaller, (e.g., 1,500,000) scales due to limited availably of source data. Along the North California and Oregon Coasts, more detailed navigation charts are simply not available from the National Ocean Service. In the Great Lakes, the Northern Boundaries fall under the jurisdiction of Canada and the Canadian Hydrographic Service. NOS coverage in these areas, while complete, is none-the-less of minimal resolution, typically 1:600,000. In spite of this, Special Projects chose to use the NOS sources in an effort to expedite the processing of the information.

Horizontal Coordinate System Units:

Degrees and decimal degrees of arc.

Longitudes all lie in the western hemisphere and are thus represented, in all cases, as values less than 0.0.

Geodetic Model

Coordinate Resolution:

Spatial data are stored as ASCII strings 8 digits in length.

Minimum distance separating adjacent vertices on an arc is: 5.0 meters, ground distance.


Status of the Current Release of the Shoreline Data

Data is currently available at the reference scale of 1:70,000, nominal.

Release date for the current data sets are:

August 24, 1994.

Maintenance/Update frequency:

None Planned.


Souces of the Current Release of the Shoreline Data

Data was sourced from National Ocean Service Coastal Series, Small Craft, General, and Harbor Charts of current addition (current as of date of capture). These charts are available for unrestricted release (sale) to the general public.

Data Sourced from the State of Florida

The source of the data from the State of Florida actually points back to the National Ocean Service. In the early 1980's, the NOS, through a private contractor, digitized the entirety of their navigational chart collection for the contiguous, lower 48 States of the Continental U.S. The State of Florida, in the mid 1980s, procured a copy of the Florida Section of this shoreline product from the NOS and made corrections and repairs to bring it up to GIS-ready status for state use. In 1991, Strategic Environmental Assessment Division received a copy of this revised shoreline from Florida and, with only minor changes to correct known problems, and a coordinate conversion from NAD27 to NAD83, incorporated this data in the current product.


Processes Used to Generate the Data

For a detailed description of the various processes which were employed in compiling this data set the reader is referred to the shoreline development processes document (PROCS file).


Data Attributes / Toplogical Associations

Spatial topology support:


Descriptive topological Associations:


Attribute items and their domains (encoding key):

Attribute Description Data type Data Size Encoded in Attribute Listing Domain Type Domain
FNODE Arcs starting, or from, node Integer 2 bytes No Discrete All positive integers from 1 to number of arcs in section
TNODE# Arcs ending, or to, node Integer 2 bytes No Discrete All positive integers from 1 to number of arcs in section
LPOLY# Id number of polygon on left side of arc Integer 2 bytes No Discrete All positive integers from 0 to number of polys in section - 1
RPOLY# Id number of polygon on right side of arc. Integer 2 bytes No Discrete All positive integers from 0 to number of polys in section - 1
LENGTH Physical length of arc, in cover units Floating point 4 bytes (F12.3) No Continuous All positive real numbers
COVER# Id number of arc; Arc/Info artifact Integer 2 bytes No Discrete All positive integers from 1 to number of arcs in section
ID Arc identification number -unique Integer 2 bytes No Discrete The set of all positive integers
L_SIDE Environment on left side of shoreline arc (see note, below) Integer 2 bytes Yes Discrete 1 = Water; 2 = Land
R_SIDE Environment on right side of shoreline arc (*) Integer 2 bytes Yes Discrete 1 = Water; 2 = Land
S_SCALE Map scale of the source chart from which the arcs were captured Integer 2 bytes No Discrete 10000 - 600000
S_CHART NOS chart catalog number for chart from which the arcs were captured Character 7 bytes No Discrete 11301 - 18800
S_DATUM Source chart horizontal reference datum Integer bytes No Discrete Set of valid horizontal datums used by NOS (02; 27; 83)
REV_DATE Source chart's date of revision Character 5 bytes No Discrete Any valid date string (mm/yy), 1/87 through 12/92
SOURCE Identifies method used to capture source data Integer 2 bytes Yes Discrete 1 = Arc/Info-ArcEdit Heads Up, 2 = Hitachi CADCore Heads Up, 3 = Digitizing Table, 4 = Estimation or truncation arc added post capture (*), 5 = Data obtained from the State of Florida
ARC_CODE Coding identifying the arc type Integer bytes Yes Discrete 1 = shoreline data arc from capture process, 3 = shoreline truncation arc -post capture addition, 5 = shoreline estimation arc -post capture modification/addition (*)
INTEGRITY Qualitative assessment of arcs accuracy based on source media Integer 2 bytes Yes Discrete 1 = master compilation -heavy gauge mylar (0.007 in), 2 = X-drawing; reproduction of master on lighter grade(0.003) mylar, 3= Water resistant paper, 4 = Data sourced from the State of Florida, 5 = Estimate or truncation arc, 6 = Unknown
(*) A brief explanation of the rational behind the left and right side topologies: By definition, a coastline or shoreline demarcates the horizontal position of a land-sea interface at a given point in time. On a map this feature is depicted simply as a line with water on one side and land on the other (the exception to this definition is the truncation arc, defined below). If we can ascertain, and we can, the left and right sides of the arcs which comprise the shoreline we can then assign the appropriate type, either land or water, to its left and right sides in the form of associated descriptive attributes.

Truncation arcs are arcs inserted into the data to provide continuity/closure in places where the cartographic information on the chart was incomplete. Often, small water bodies (rivers, streams, and creeks), in locations beyond the point of navigability are terminated to facilitate the insertion of non-cartographic information such as title blocks and notations. Continuity of the data, a requirement our data set specification, is interrupted at these locations if they are captured and retained as depicted on the navigation chart. To reestablish the necessary topological continuity an artificial closure arc is placed across the truncated section of shoreline. These arcs make no attempt to simulate the position of the missing shoreline section(s), but rather simply terminate the feature. To easily identify these arc features in the data field they are given the attribute codes: SOURCE = 4 and ARC_CODE = 3.

Estimation arcs are used for two purposes: first, to fill in gaps in the shoreline as depicted on the chart (other than those areas which would be considered truncations), and secondly, to identify captured (digitized) shoreline arcs which have been modified in some way either for error rectification or edge matching adjustments. The span of these arcs range from five meters to several tens of meters in length. In the first case, estimator arcs attempt to simulate or mimic the actual shape or course of the coastline in the missing area. Insertion of these arcs into the data is done using heads up methods with the appropriate navigational chart(s) as a guide. In the second case, an existing arcs terminal to node is moved from its original captured location to a position where it can be connected to the concomitant arc's node from an adjacent chart. Additional vertices may then be added to replicate the course of the original information. Modification of existing arcs was carried out such that disruption of the information was minimized. Estimate arcs are identified in the data by the codes: SOURCE = 4, ARC_CODE = 5.

If the accuracy of the data could not be assessed and thus categorized into one of the five qualitative integrity classes, the arc was classified with an integrity of unknown. Most of the arcs grouped into the unknown category were those captured early in the project. During that time source materials (primarily master compilations and X-drawings) were assumed to be of equal stability and accuracy. This was not, however, the case. Once this disparity was recognized, source tracking procedures were implemented and the integrity of the captured information, based on the stability and clarity of the source media was tracked and assessed.



Distribution Information

This data was produced by, and is available from:

NOAA/NOS Special Projects The Strategic Environmental Assessments Division
1305 East-West Hwy, 9th FL, N/MB7
Silver Spring, MD 20910
(301)-713-3000 -voice, general office
(301)-713-4384 -facsimile, general office


This product is also distributed by:

Marine Geology and Geophysics Division
The National Geophysical Data Center
National Ocean and Atmospheric Administration
Mail Code E/GC3 325 Broadway
Boulder, CO 80303-3328
303-497-4384 -voice
303-497-6513 -facsimile

You may access these files through the download page on this site or the shoreline files are available through NOAA's National Geophysical Data Center:



Data format and Compression:

The data is distributed via this website in ESRI shapefile format. Please visit the download page to access these files

When originally released the data was distributed in two ASCII formats.

The file set listed with the extension, .GEN, were created using the ArcInfo UNGENERATE Command. These are available for those who wish to access the data directly. The second ASCII group conforms to the public domain Boundary Named ASCII File format (BNA). Several popular mapping and GIS packages read and write to the latter format.

To obtain data in either of these formats please contact the NOAA NOS Special Projects office directly.