Frequently Asked Questions
What is a T-sheet?
The term "T-Sheet" refers to topographic sheets (shoreline manuscripts) that were compiled from maps derived in the field with a planetable, in the office from aerial photos, or a combination of the two methods. The National Ocean Survey, previously known as U.S. Coast and Geodetic Survey, created T-sheets from surveys conducted from 1834 to 1980 and TP-sheets after 1968. These manuscripts have been assigned registry numbers of T or TP series to distinguish a topographic survey from its corresponding H or hydrographic survey series. These shoreline manuscripts are the authority for the high-water line and may also include features such as roads, prominent buildings, alongshore features, and rocks. The T, TP, and H survey series were used as base maps to construct nautical charts primarily used for navigation.
Where can I get a T-sheet?
Scanned copies of T-sheets can be requested by emailing firstname.lastname@example.org. In some cases, the scanned raster images have already been geo-referenced. T-sheet coverage is depicted in one index for the earlier years (late 1800s through the 1930s), and a separate index for the later years (1940s and 1950s).
Vector shoreline data that is derived from T-sheets can be downloaded through the NOAA Shoreline Data Explorer, but this site is not comprehensive in that it does not include shorelines for every T-sheet that has been converted to vector.
Efforts are currently underway to redevelop the NOAA Shoreline Data Explorer, so that it will provide access to all raster and vector T-sheet data. The new site will have an upgraded interface providing the ability to search by state, area of interest, and T-sheet number.
What is the total length of the U.S. shoreline?
NOAA’s official value for the total length of U.S. tidal shoreline is 95,471 statute miles (The Coastline of the United States [NOAA/PA 71046], 1975). The tidal shoreline figures were measured by hand in 1939-40 with a recording instrument on the largest-scale charts and maps then available. Shorelines of outer coast, offshore islands, sounds, bays, rivers, and creeks were included to the head of the tidewater or to a point where tidal waters narrow to a width of 100 feet. The total length of tidal shoreline includes measurements of the coastal states as well as the outlying U.S. territories and possessions. For the Great Lakes, the shoreline lengths were measured in 1970 by the International Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data.
Is there a "national shoreline?"
Shoreline data that is generated by the NOAA National Geodetic Survey (NGS) for the purpose of nautical charting is what constitutes the National Shoreline. This data set includes both MHW and MLLW. Since it is regularly updated, the National Shoreline cannot be accessed as a single discrete data set, but the individual vectors are available (see NOAA National Shoreline).
What is the legal U.S. shoreline?
There is no legal reference that designates one specific shoreline as the legal shoreline. Furthermore, there is no simple answer to this question as there are many legal, technical, and general uses of the terms related to shoreline (shoreline, coastline, baseline, mean high-water line, mean-low water line, etc.).