Amtrak, the national intercity passenger railroad, inherited a 1930s-era 11 kV 25 Hz electrification system from the Pennsylvania Railroad (PRR), which it is slowly modernizing, and has completed two electrification projects on its own lines.

Amtrak's electrification is primarily concentrated in the Northeast Corridor (NEC), which is the busiest rail line in North America, stretching from Washington, D.C., to Boston, Massachusetts. This corridor is fully electrified, allowing high-speed trains like the Acela and the Northeast Regional to operate using overhead catenary systems. Additionally, the Keystone Corridor between Philadelphia and Harrisburg is electrified. However, the vast majority of Amtrak's national network, including long-distance routes like the Empire Builder, the California Zephyr, and the Southwest Chief, is not electrified. On these routes, Amtrak relies on diesel-electric locomotives. As of 2026, Amtrak is in the midst of a massive fleet modernization program, introducing the new Airo trainsets, many of which are "dual-mode," meaning they can run on electric power when under wire and switch to diesel for non-electrified sections. While there are ongoing infrastructure projects to upgrade electric systems, the immense cost and logistical challenges of electrifying thousands of miles of freight-owned track mean that diesel remains the standard for most of the country.