In the United States, most wholesale electricity markets are operated by seven Regional Transmission Organizations (RTOs) and Independent System Operators (ISOs). These grid operators function like the air traffic controllers of the power system—they don’t own power plants or transmission lines but instead coordinate, control, and monitor electricity flow across wide geographic areas to ensure the lights stay on every second of every day.
Where They Operate
Some RTOs and ISOs manage power systems across multiple states—like PJM Interconnection, ISO-New England (ISO-NE), Midcontinent Independent System Operator (MISO), and the Southwest Power Pool (SPP)—while others oversee a single state, such as the New York Independent System Operator (NYISO), the California ISO (CAISO), and the Electric Reliability Council of Texas (ERCOT).
Why They Matter
RTOs and ISOs provide a competitive, transparent marketplace where power producers—like EPSA’s member companies—can sell electricity based on price, reliability, and performance. This structure rewards efficient operations and innovation, helping to keep electricity costs lower for consumers while ensuring reliability.
How They Support Reliability and Innovation
These markets are designed to balance supply and demand in real time, maintain grid reliability, and plan for long-term transmission and resource needs. As the grid evolves, RTOs and ISOs are adapting to integrate renewables, storage, and growing energy demand from AI and electrification—making them a key platform for building a reliable energy system.
EPSA’s Role
EPSA advocates for well-functioning, competitive electricity markets and policies that allow private investment to meet America’s growing power needs. Our members participate in RTO and ISO markets nationwide, helping to ensure reliable, affordable, and sustainable electricity for millions of consumers.
