The transmission grid that delivers electricity from power plants is a vital piece of America’s infrastructure. It is also good at hiding its flaws. People may notice the towers and wires marching across the landscape or the local substations that step down the voltage so electricity can be distributed to homes and businesses, but the transmission grid does not show congestion like highways do or flooding like burst water mains do. Nevertheless, the grid needs a major upgrade. If the U.S. is going to switch from dirty fossil fuels to cleaner, more renewable wind and solar power—or even nuclear—the transmission system must be vastly expanded to reach the remote deserts and high plains where the sun shines most and the wind blows hardest. Furthermore, if the country wants to protect itself against increasingly large blackouts, which cost tens of billions of dollars or more a year, it needs to modernize the grid as well.