It’s not just Amtrak, you can see Metra, LIRR, Metro North, and MBTA routes on the map around their respective cities. And I’m not convinced there are hundreds of regional rail services in America, maybe if you count heritage railroads, but even then I think you won’t be getting too far above 100 and those don’t actually take people from point A to point B generally, so it’s arguable that they count as passenger rail service
I think it’s only Amtrak, the main Intercity passenger rail service. There’s a ton more freight rail, and hundreds of smaller regional rail services.
It’s not just Amtrak, you can see Metra, LIRR, Metro North, and MBTA routes on the map around their respective cities. And I’m not convinced there are hundreds of regional rail services in America, maybe if you count heritage railroads, but even then I think you won’t be getting too far above 100 and those don’t actually take people from point A to point B generally, so it’s arguable that they count as passenger rail service