High-voltage power lines span borders across the U.S., with many grid operators overseeing multi-state regions and even single-state grids exchanging power with neighboring states. Given the interconnected nature of the electric grid, coordination between states on infrastructure deployment is essential to accelerating grid expansion. A collaborative approach among decision-makers and stakeholders—such as state and local officials, business leaders, consumer groups, and others—can yield significant benefits for the grid and the communities it serves. Federal policy should prioritize and support these efforts.

While multi-state coordination of transmission network expansion is inherently more complex than individual state-led infrastructure projects, regional and interregional network upgrades often yield significantly greater benefits than smaller, local lines. Numerous examples of successful state-to-state alignment offer valuable lessons as the U.S. works to modernize its power grid. Moreover, a variety of promising cross-state initiatives are currently underway, building on these historical precedents and paving the way for new infrastructure development.

Here, we highlight six examples of transmission development collaborations that showcase the diverse ways states and stakeholders can work together. The states involved in these examples span a wide political and geographical spectrum, featuring various electricity market structures, power generation mixes, and state energy policies.

  1. Southwest Power Pool (SPP) Priority Projects: The Southwest Power Pool serves as the grid operator for a vast region that includes the Dakotas, Nebraska, Kansas, Oklahoma, and portions of nine surrounding states. In 2010, SPP approved a portfolio of six transmission projects. These projects, with an estimated benefit of $3.7 billion, were successfully completed. The $1.3 billion portfolio’s development was informed by input from key stakeholders, including the SPP Regional State Committee, which comprises utility commissioners from each of the SPP member states.
  2. North Plains Connector: North Dakota Governor Doug Burgum and Montana Governor Greg Gianforte have both praised the development of this $3.6 billion high-capacity transmission line connecting the two states. An independent transmission company is developing the interregional power line in partnership with two utilities. The project received a significant boost when the Montana Department of Commerce successfully applied for a DOE grant, with additional backing from the North Dakota Industrial Commission, which issued a letter of support for the application.
  3. Carolinas Transmission Planning Collaborative: Duke Energy is an investor-owned utility that operates a grid spanning North Carolina and much of South Carolina. With input from key stakeholders, the utility has developed a proactive, scenario-based transmission planning process designed to address multiple drivers of grid update needs. A coalition of influential clean energy businesses and environmental groups from both states have formally endorsed Duke’s application to FERC to authorize the process.
  4. Susquehanna to Roseland Transmission Line: This $1.4 billion, 146-mile interstate project was jointly developed by Pennsylvania and New Jersey utilities and completed in 2015. PJM Interconnection, the grid operator for 14 states in the mid-Atlantic, identified the need for the line to meet reliability requirements, and the state utilities commissions in Pennsylvania and New Jersey both authorized their portions of the line.
  5. WestTEC: The Western Transmission Expansion Coalition is developing a voluntary interregional transmission planning process covering all three grid planning regions in the western U.S. – NorthernGrid, the California Independent System Operator, and WestConnect. The initiative features “broad participation from key stakeholders outside of transmission owners, including central participation from states and tribes.”
  6. Northeast Intertie: New York and the six New England states joined forces to apply for federal funding to support investment in upgrading the high-voltage intertie connecting the New York and New England grids. The funding request emerged from cooperative efforts to explore options for enhancing the intertie. A comprehensive analysis determined that the project would save customers over $1 billion—exceeding the upgrade cost—by increasing the line’s voltage, enabling it to carry more power efficiently. 

Stakeholders have numerous opportunities to collaborate in identifying and advancing beneficial transmission network upgrades. The examples above illustrate a range of approaches, including planning processes, analytical efforts, infrastructure authorizations, and funding applications. The key players in these efforts also span a wide spectrum, which includes state utility commissioners, governors, utilities, clean energy and transmission developers, environmental groups, and tribes. 

While this is not an exhaustive review, numerous examples demonstrate states’ and grid stakeholders’ success when aligning on infrastructure deployment. These collaborations have brought significant benefits to their regions—outcomes that would not have been possible without multi-state coordination. The success of these collaborations underscores the potential for future progress through similar partnerships. State and local leaders, along with stakeholders, have the chance to engage with their neighbors, and federal policy can play a crucial role in supporting this engagement. Proactively fostering these opportunities can accelerate vital infrastructure development across the U.S.