James McCalley, an Anson Marston Distinguished Professor in Engineering and the Jack London Chair in Power Systems Engineering at Iowa State University, has studied the U.S. electrical grid for years.
He's helped study the costs and befefits of connecting the country's grids to share and move electricity. Here's a release about that study from the archives: https://www.newswise.com/articles/study-shows-value-of-sharing-energy-including-wind-and-solar-across-america-s-grids
He's also co-author of a recent report about the U.S. trailing the world in development of these macro grids: https://www.news.iastate.edu/news/2020/12/08/macrogrids
He recently wrote about “A Macrogrid Design for the 21st Century,” https://www.esig.energy/a-macrogrid-design-for-the-21st-century/
Here's more about McCalley: https://www.ece.iastate.edu/ece-directory/profile/jdm/
He's generally available my email or cell phone.