This document contains the distances between the ports located in the United States, it also provides users with the distances between ports in the Great Lakes as well as Canadian ports and ports in St. Lawrence river. Subject distances have been measured along navigable track lines. The geographical coordinated of arrival and departure have been stated for centrally located piers inside ports.
Note that all distances between ports are in nm, i.e. nautical miles, except the distances in the tables addressing Mississippi River System as well as Great Lakes plus other inland waters - subject distances are given in statute miles. In case two or more navigation routes converge, they have been shown in capital letters. The publication is usually prepared and released by NOS, standing for the National Ocean Service, in collaboration with the NOAA, i.e. National Oceanic and Atmospheric Administration, and Office of Coast Survey.
The title of the publication is pretty clear and does not require any further explanation - it is intended to provide users with the distances they will use for navigation when planning their voyages. The book starts with a part providing general information and followed by the main content with the tables giving the distances. Some of the supplementary tables are also provided, e.g. for the estimation of transit time, determination of the wind speed etc.