The North American electric transmission network was developed under the guidance of the North American Electric Reliability Council (NERC) to enhance the reliability of electricity supply. The network also allows sale and marketing of electric power by one utility to another. Electricity marketing has taken on a much more prominent role with restructuring of the electric utility industry. As a result, long-distance sales of electric power have greatly increased the loading of some transmission lines, and have led to congestion on the transmission network. Recent system failures such as the northeast blackout of 2003 have highlighted the need for increased capacity. While some upgrades of existing infrastructure will be undertaken, some of this capacity must be provided through new transmission lines
