HIFLD Open 24NM Contiguous Zone

Name: HIFLD Open 24NM Contiguous Zone
Published: 2025-09-30
License: https://creativecommons.org/share-your-work/public-domain/pdm

Principal Investigator(s): View help for Principal Investigator(s) National Oceanic and Atmospheric Administration; United States Department of Homeland Security

Version: View help for Version V1

Name	File Type	Size	Last Modified
24nm-contiguous-zone-geojson.zip	application/zip	651.3 KB	09/30/2025 10:33:AM
24nm-contiguous-zone-shapefile.zip	application/zip	625.3 KB	09/15/2025 05:38:AM
metadata.xml	application/xml	8.7 KB	09/30/2025 10:34:AM

Project Citation:

National Oceanic and Atmospheric Administration, and United States Department of Homeland Security. HIFLD Open 24NM Contiguous Zone. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2025-09-30. https://doi.org/10.3886/E238492V1

Project Description

Project Title: HIFLD Open 24NM Contiguous Zone

Summary:

Maritime Limits and Boundaries of United States of America

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). The outer limit of each of these zones is measured from the U.S. normal baseline, which coincides with the low water line depicted on NOAA charts and includes closing lines across the entrances of legal bays and rivers, consistent with international law. The U.S. baseline and associated maritime limits are reviewed and approved through the interagency U.S. Baseline Committee, which is chaired by the U.S. Department of State. The Committee serves the function of gaining 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 extent of U.S. maritime zones do not exceed the breadth that is permitted by international law. In 2002 and in response to mounting requests for digital maritime zones, NOAA launched a project to re-evaluate the U.S. baseline in partnership with other federal agencies via the U.S. Baseline Committee. The focus of the baseline evaluation was NOAA's largest scale, most recent edition nautical charts as well as supplemental source materials for verification of certain charted features. This dataset is a result of the 2002-present initiative and reflects a multi-year iterative project whereby the baseline and associated maritime limits were re-evaluated on a state or regional basis. In addition to the U.S. maritime limits, the U.S. maritime boundaries with opposite or adjacent countries as well as the US/Canada International Boundary (on land and through the Great Lakes) are also included in this dataset.

Original Distribution URL: https://hifld-geoplatform.hub.arcgis.com/

Scope of Project

Subject Terms: HIFLD Open; GIS; water; ocean; boundaries

Geographic Coverage: United States

Time Period(s): 1/1/2024 – 12/31/2024

Data Type(s): geographic information system (GIS) data

Collection Notes: Archived from the HIFLD Open GIS data repository, which was deactivated on August 26, 2025

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Published Versions

V1 [2025-09-30]

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