Shorelines in the United States are a federal responsibility. The organic act was signed in 1807. Both are defined as the line of contact between land and selected water elevations. In common usage it is often used as a permanent high-water boundary. For non-tidal waters it is normally mean water level.
Attributes refer to the nature of shoreline features, such as rocky, sandy, muddy, and the like.
Other more descriptive reference standards are exemplified in Table 1. For discussion of the details of elevation contours and datum references see Crowell et al, 1991.