The most notable example of quadruple track in the United States, and perhaps the only four-track section of mainline therein, was the Pennsylvania Railroad's main corridor through the heart of Pennsylvania around the famous Horseshoe Curve. This line is now owned by Norfolk Southern. Other examples include the Hudson and New Haven Lines, both of which are shared between Metro-North and Amtrak in New York and Connecticut. The New Haven Line is quadruple track along its entire length, while the Hudson Line is only quadruple tracked along the shared portion from Riverdale to Croton–Harmon and along the shared track from Grand Central Terminal to Yankees–East 153rd Street. Amtrak's Northeast Corridor is quadruple tracked in most portions south of New Haven, but also has a few triple-track segments.