In the case of some rivers such as the Columbia, the length listed in the table below is solely that of the main stem.
In the case of others such as the Mackenzie, it is the combined lengths of the main stem and one or more upstream tributaries, as noted.
Excluded from the list are rivers such as the Dauphin, a short connecting link between lakes Manitoba and Winnipeg, with main stems of 100 km (62 mi) or less.
[1] The drainage basins of these nine rivers extend into both countries; in addition, the drainage basins of six others—the Fraser, Assiniboine, South Saskatchewan, Saskatchewan, Nelson, and Winnipeg—extend into the United States even though their main stems flow entirely within Canada.
"It seems", she said, "that the wisest course is to regard data tables such as the present one as showing the general ranks of rivers, and not to place too much importance on minor (10–20%) differences in figures.