Amtrak just expanded route coverage in the Transit section of the Apple Maps app to include all of the United States. That means Amtrak lines will now show up as an option (along with subways, buses and ferries) if your itinerary is in the path of a relevant train.
The train routes are only displayed if you search a city with transit directions supported by Apple Maps, but the coverage area now extends to all major cities in the country as well as Montreal and Vancouver in Canada.
If you're a frequent Apple Maps user, the Amtrak train information in iOS will feel familiar. You can click on the entrances and exits within a particular train station to see more details about the location of stars, elevators, escalators, and other accessibility options.
The additional Amtrak train lines probably won't draw Apple Maps deserters back from Google alone, but it could be a reason for frequent commuters and travelers to keep the native app around just in case.