The U.S. electricity transmission system is an extensive, interconnected network of high-voltage power lines that transport electricity from generators to consumers. The transmission system must be flexible enough, every second of every day, to accommodate the nation's growing demand for reliable and affordable electricity.

The transmission system was built over the past 100 years by vertically integrated utilities that produced and transmitted electricity locally. Small interconnections between neighboring utilities existed, but they were created to increase reliability and share excess generation. Over the past 10 years, we have introduced competition into wholesale electricity markets to lower costs to consumers by spurring needed investments in generation and increasing the efficiency of operations. Today, our transmission system acts as an interstate highway system for wholesale electricity commerce.