Rivcst.e00 was calculated in Plate Caree equidistant cylindrical projection. Distance was measured from the coast or a sea-navigable waterway, excluding coastline in the Arctic and sub-Arctic regions above the winter extent of sea-ice and the rivers that flow to it. The source of winter sea-ice extent is: NGS (National Geographic Society). 1995. The World: Political (map). Washington, D.C. The source of the digital coastline is: ESRI (Environmental Systems Research Institute) 1996. ArcWorld Supplement Data Reference and User's Guide. Redlands, California. Rivers categorized as navigable in the ArcAtlas (ESRI, 1996) database are pared down according to three rules using information taken from Rand McNally (1980), Brittanica Online (1998), and Encyclopedia Encarta (1998): whether a river accommodates vessels with a minimum draft of approximately 3 meters (anything smaller is not considered ocean-going); the point at which a navigable river becomes obstructed by falls, rapids, locks or dams; and whether the river is frozen during winter. The references for the sources listed above are: Rand McNally and Co. 1980. Encyclopedia of World Rivers, New York: Rand McNally and Co. Britannica Online. 1998. Http://www.eb.com. Encyclopedia Encarta. Http://encarta.msn.com.

This GIS data was created as part of The Center for International Development’s ongoing research into the role of geography in economic development (see www.cid.harvard.edu/economic.htm). It was created between 1998 and 1999. Please reference CID if you use this data in a publication.