The SPATIAL LOCATION of canals is based upon modern and historical U.S. topographical maps (United States Department of the Interior, U.S. Geological Survey), especially those from the mid to late twentieth century that explicitly make features like old canal beds.

The EXISTENCE of early canals based upon contemporary maps in the Library of Congress (such as Henry S. Tanner, A Description of the Canals and Railroads of the United States, Comprehending Notices of all the Works of Internal Improvement Throughout the Several States. New York: T.R. Tanner & J. Disturnell (1840); digital image: http://hdl.loc.gov/loc.gmd/g3701p.rr000070), the David Rumsey collection (www.davidrumsey.com) and Henry Varnum Poor, History of the railroads and canals of the United States of America exhibiting their progress, cost, revenues, expenditures & present condition, New York: J.H. Schultz & Co. (1860) as well as more modern reconstructions such as that by Carter Goodrich, Canals and American economic development. New York: Columbia University Press (1961).

File contains source references regarding each canal together with a date when each stretch of canal opened and closed (2100 = still in operation)

In general, rivers that were improved and called "navigations" are treated as rivers rather than canals EXCEPT for the Schuylkill and Bald Eagle and Spring Creek navigations where the man-made waterways exceeded the distance in natural channels.

Updated March 15, 2017 to correct western terminus of the original Erie Canal (thanks to Jason Knight of SUNY Buffalo)

Digitized maps were geo-referenced using ArcGIS 10’s spline algorithm against the National Historical Geographic Information System’s 2009 TIGER-based historical state and county boundary files (see www.nhgis.org) and the U.S. National Atlas’s database of cities and town.

See Jeremy Atack "Procedures and Issues Relating to the Creation of Historical Transportation Shapfiles of Navigable Rivers, Canals, and Railroads in the United States" available at https://my.vanderbilt.edu/jeremyatack/files/2015/09/HistoricalTransportationSHPfilesDocumenation.pdf. Also see Jeremy Atack, "On the Use of Geographic Information Systems in Economic History" Journal of Economic History, 73:2 (June 2013): 313-338. Also available at https://my.vanderbilt.edu/jeremyatack/files/2011/08/EHAPresidentialAddress.pdf