The following links contain zipped shapefiles of the Three Nautical Mile Line, Territorial Sea (12 naut. mi.), and Contiguous Zone (24 naut. mi.) as represented on NOAA's nautical charts. For more information about each dataset, metadata is also provided.  This site will be updated frequently with new digital limits of the maritime zones.  And, these ambulatory limits are subject to revision based on accresion or erosion of the charted low water line.

If you do not have software to view these shapefiles, ESRI has a free viewer to download at http://www.esri.com/software/arcexplorer/download.html.  To view the shapefiles in any GIS, you will need to extract the shapefiles from the zip file.  Within ESRI's ArcExplorer, you can load and view the shapefiles using "Add Layers."