Shoreline Mileage

The 2021 Tabulation

The 2021 tabulation used NOAA’s Continually Updated Shoreline Product (CUSP) , a continuously updated vector shoreline derived from both NOAA (primarily National Shoreline) and contemporary non-NOAA sources. Referenced to mean high water where applicable, CUSP integrates multiple technologies, including lidar, mono- and stereoscopic compilation, and automated feature extraction.

The CUSP shoreline was clipped to a 500 meter buffer created from shoreline on the largest scale electronic navigational charts at the time. Unfortunately, this approach proved unreliable in Alaska due to the age of the shoreline and amount of change. Instead, the CUSP shoreline was clipped to the head of tide waters.

Since the CUSP vector is a multi-scale product, it was modified to simulate a 1:24,000 scale for all states and territories through coastal mapping rules and simplication. Inclusion/exclusion compilation rules for streams, rivers and other narrow waterways were determined using the 2019 NGS Shoreline Mapping Scope of Work. It states, “Streams that are connected to the shoreline, and are at least 0.5 mm wide, are considered to be shoreline themselves and shall be compiled using an appropriate code in the Shoreline class”. At a map scale of 1:24,000, this is equivalent to 12 meters on the ground. Based on this rule, streams, rivers and other waterways that were less than 12 meters wide were removed from the CUSP vector.

The vector was then simplified using the Bend Simplify algorithm. This algorithm was used because it is a shape-preserving simplification method that produces vectors that are similar to the original shoreline. It ensures that the simplified geometry retains the topological relationships of the original data by iteratively removing points based on a given tolerance while maintaining topological consistency.

A final check was performed to remove any remaining landlocked ponds or narrow channels. A 6 meter buffer was created around the shoreline mileage vector. The Identify Narrow Polygons Tool in ESRI ArcMap was then used to identify buffer segments that were less than 12 meters wide. Each identified segment was visually inspected in a GIS and the vector modified as needed.

Shorelines were measured in geodesic length (which accounts for the Earth's curvature) within ESRI ArcGIS Pro and then Global Mapper to verify results. Shorelines, breakwaters, jetties, groins, and rocks were included in the tabulation, reported in statute miles. The United States and its territories have 221,923 statute miles of shoreline. It should be noted that this new mileage calculation is not considered official and users should evaluate the use of these numbers based on their own application.

Atlantic Coast

State/Territory	Statute Miles		State/Territory	Statute Miles
Connecticut	1,105		New Jersey	4,759
Delaware	1,232		New York	3,112
Florida	22,447		North Carolina	7,548
Georgia	5,107		Pennsylvania	202
Maine	5,000		Rhode Island	616
Maryland	7,149		South Carolina	7,009
Massachusetts	2,510		Virginia	8,016
New Hampshire	247		Washington, D.C.	61

Carribean

State/Territory	Statute Miles		State/Territory	Statute Miles
Puerto Rico	923		U.S. Virgin Islands	286
Navassa	6

Gulf Coast

State/Territory	Statute Miles		State/Territory	Statute Miles
Alabama	1,358		Louisiana	30,916
Mississippi	1,281		Texas	7,207

Pacific Coast

State/Territory	Statute Miles		State/Territory	Statute Miles
California	6,094		Oregon	2,734
Washington	5,165

Great Lakes

State/Territory	Statute Miles		State/Territory	Statute Miles
Illinois	218		Indiana	107
Michigan	6,295		Minnesota	324
New York	1,911		Ohio	868
Pennsylvania	92		Wisconsin	1,724

Alaska

State/Territory	Statute Miles
Alaska	76,231

Pacific Islands

State/Territory	Statute Miles		State/Territory	Statute Miles
American Samoa	145		Hawaii	1,373
Nihoa	3		Necker	2
French Frigate Shoals	5		Laysan	5
Lisianski	3		Pearl and Hermes Atoll	6
Kure Atoll	5

Northern Marianas Islands

State/Territory	Statute Miles		State/Territory	Statute Miles
Guam	151		Rota	34
Saipan	57		Tinian	39
Farallon de Pajaros	5		Sarigan Island	8
Farallon de Medinilla	5		Asuncion Island	8
Agrihan	23		Alamagan Island	11
Guguan	7		Anatahan	21
Pagan Island	34		Maug Islands	11
Aguijan	9

Misc Insular or Outlying Areas

State/Territory	Statute Miles		State/Territory	Statute Miles
Baker	3		Howland	4
Jarvis	5		Palmyra	35
Johnston	9		Kingman Reef	1
Midway Islands	12		Wake Island	24