Transmission Congestion in the U.S.

When the grid cannot deliver the lowest-cost generation to load, more expensive generation is dispatched instead, raising prices. This cost is reported as “transmission congestion” in organized wholesale markets administered by regional transmission organizations (RTOs) and independent system operators (ISOs). Since 2019, Grid Strategies has published an annual report examining the costs and causes of transmission congestion, according to the latest data from RTOs/ISOs.

The latest report, “Transmission Congestion for 2024,” finds that total congestion costs surpassed $12 billion in 2024, marking the fourth year that congestion costs have stayed above $10 billion. Between 2016 and 2020, congestion costs averaged between $6-8 billion a year. This “new normal”—driven by inadequate transmission expansion, rising electricity demand, and extreme weather—threatens to drive up rates for consumers and hinder overall reliability.

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About the methodology: This data is compiled using congestion costs reported by market monitors for RTOs/ISOs. To estimate a national congestion cost figure that includes non-RTO/ISO regions, this report scales the known RTO/ISO congestion costs in Table B1 in the Appendix according to the peak load of the same regions when compared to total U.S. load.

Past Reports