Maritime limits and boundaries for the United States are measured from the official U.S. baseline, recognized as the low-water line along the coast as marked on the NOAA nautical charts in accordance with the articles of the Law of the Sea. The Office of Coast Survey depicts on its nautical charts the territorial sea (12 nautical miles), contiguous zone (24nm), and exclusive economic zone (200nm, plus maritime boundaries with adjacent/opposite countries).
Click on limit or boundary for specific information. Data shown is available for download.
Dynamic Map Services
Dynamic map services are updated whenever we make updates to our data. If you are using maritime boundaries in a web map or as a background for other data, we recommend using our dynamic services, as they will seamlessly update in your application. For information about using dynamic map services, please see the frequently asked questions page (FAQ).
NOAA is responsible for depicting on its nautical charts the limits of the 12 nautical mile territorial sea, 24 nautical mile contiguous zone, and 200 nautical mile Exclusive Economic Zone (EEZ). These zones are highlighted in orange.
The territorial sea is a maritime zone over which the United States exercises sovereignty. Sovereignty extends to the airspace above and to the seabed below the territorial sea. The U.S. territorial sea extends 12 nautical miles from the baseline.
The contiguous zone of the United States is a zone contiguous to the territorial sea. In this zone, the U.S. may exercise the control necessary to prevent and punish infringement of its customs, fiscal, immigration, cultural heritage, or sanitary laws and regulations within its territory or territorial sea. The U.S. contiguous zone is measured 24 nautical miles from the baseline.
Exclusive Economic Zone (EEZ)
The exclusive economic zone (EEZ) of the U.S. extends 200 nautical miles from the territorial sea baseline and is adjacent to the 12 nm territorial sea of the U.S., overlapping the 12-24nm contiguous zone. Within the EEZ, the U.S. has:
(See Presidential Proclamation No. 5030, March 10, 1983.)
Certain U.S. fisheries laws use the term “exclusive economic zone” (“EEZ”). While its outer limit is the same as the EEZ on NOAA charts, the inner limit generally extends landward to the seaward boundary of the coastal states of the U.S. For the seaward limit of the states jurisdiction under the Submerged Lands Act, please see GIS Data / Shapefiles.
Maritime boundaries with adjacent and opposite countries are established through agreement and treaties with these neighboring nations. For more information about these treaties, visit the Department of State information page on maritime boundaries.
In 2011, the Office of Coast Survey completed a multi-year project to merge all of the regional maritime limits into a single seamless digital dataset. Because U.S. maritime limits change, based on accretion or erosion of the charted shoreline, Coast Survey, in conjunction with the U.S. Baseline Committee, continually maintains the dataset. When NOAA releases a new nautical chart the maritime limits and boundaries are updated as needed. This page highlights regional or local updates to the dataset.
September 13, 2013
Released version 4.1 with changes as follows:
July 22, 2013
Released version 4.0 with changes as follows:
July 20, 2012
Released version 3.1 with changes as follows:
April 16, 2012
Released version 3.0 with changes as follows:
The Bureau of Ocean Energy Management (BOEM) manages and disseminates the Submerged Lands Act federal/state boundaries. Electronic data is here. Go to the links under “GIS Data / Shapefiles” to download data for a specific region. Note: the Gulf of Mexico dataset is in the sub-link, "Gulf of Mexico Geographic Mapping Data."
The U.S. maritime limits are projected from a "normal baseline" derived from NOAA nautical charts. A "normal baseline" (as defined in the 1958 Geneva Convention on the Territorial Sea and the Contiguous Zone and Article 5 of the United Nations Convention of the Law of the Sea) is the low-water line along the coast as marked on official, large-scale charts. Since "low-water line" does not reference a specific tidal datum, the U.S. applies the term to reference the lowest charted datum, which is mean lower low water (MLLW).
The maritime limits are created using “envelope of arcs,” a method by which one rolls a virtual circle along the charted low water line and selects salient points. These salient points are called "contributing baseline points." Arcs generated from these baseline points are blended together to form a continuous limit line or envelope of arcs.
The U.S. Baseline Committee reviews and approves the limits of all maritime zones on NOAA charts. It gains interagency consensus on the proper location of the baseline, using the provisions of the 1958 Convention on the Territorial Sea and the Contiguous Zone, to ensure that the seaward extents of U.S. maritime zones do not exceed the breadth permitted by international law. Current members of the Committee include the Departments of State (Chair), Commerce (NOAA), Justice, Interior (BOEM), and Homeland Security (Coast Guard), among others.
The primary triggers for updates include accretion or erosion of the charted low water line by approximately 500 meters or more, or changes to low tide elevations (i.e., rocks awash) as a result of new hydrographic survey information. The Office of Coast Survey and the Baseline Committee will investigate these changes for new edition chart. There are approximately 12 new editions issued each month, and a small number of these charts depict features that impact the U.S. baseline or maritime limits. The Baseline Committee, which meets four to six times per year, reviews and approved all proposed revisions.
Another trigger for change may be the U.S. ratification of a new treaty with a neighboring coastal State. Some areas for future change include the U.S. waters adjacent to Canada, the Bahamas, Kiribati, Tonga, and the Federated States of Micronesia, to name a few.
Depending on the level of change (see Weekly Chart Updates), the Office of Coast Survey may update the digital U.S. maritime limits and boundaries as often as every few months in certain areas. Though we provide both dyanmic and static datasets, we recommend using our dynamic data services to ensure the most up-to-date version of the U.S. maritime limits and boundaries. We provide an archive of past updates to explain what has changed in each release of the data.
We offer dynamic data is two formats: OpenGIS ® Web Map Service (WMS) and proprietary ESRI REST service.
The WMS can be used in various desktop GIS software as well as web mapping applications. The WMS link leads to the GetCapabilities page, which provides easy-to-read, detailed information about the data as well as the necessary link to load the data into a GIS or web mapping application. Open Geospatial Consortium (OGC) provides more information about web mapping services.
For users who prefer to work within the ESRI software environment, we provide an ESRI REST (Representational State Transfer) service. This service can be used in ESRI’s ArcGIS Desktop software or in ESRI’s free ArcGIS Explorer Desktop. It can also be added as a layer in web mapping services, such as ArcGIS Online.
The dataset includes specific information about each maritime boundary segment. Attributes for the data are:
Because of a difference in the chart printing schedule and the digital data update schedule, the digital data and the paper charts might not always be identical. In the event that the digital product and the paper charts differ, the maritime limits and boundaries on the paper charts take precedence.
We find that most people who seek this line are actually looking for the Submerged Lands Act federal/state boundary provided by BOEM (see FAQ #1). For those seeking the ambulatory three nautical mile territorial sea limit, we recommend that you use the seamless raster nautical chart service provided by the Office of Coast Survey.