The rail network of North America continues to consolidate, but it is beginning to become transnational as well. Since NAFTA, Canadian National has acquired several US regional railways, and Kansas City Southern has purchased Transportacion Ferroviaria Mexicana — both part of a drive towards a "NAFTA Rail" alliance. Together the eight Class I railroads (defined as having more than $277.7m in revenues) shown on the map control approximately two thirds of all rail on the continent. There are more than four hundred Class II and III railways.