Overall? It's not happening privately. Cross-country rail is expensive and pointless when planes will beat the long distances greater than flying from NYC to London.
What can be done is when Amtrak is made, instead of keeping all the costly long distance lines running, separate rail service into regions and focus on serving the region instead of the entire USA. There can be one or two long distance services but majority should stick to the regions, like how they do it in the NE. Splitting it up into: West Coast, Southwest, Texas, Rockies, Southeast, Midwest, and Northeast-MidAtlantic would be the best way to do it, emulating how it's done with the likes of the NE Regional.
If done regionally like this, federal intercity high-speed rail can be done (if Amtrak builds its own trackage) and there can be overlap hubs to facilitate interchange between regions which can encourage growth for that city. For example Richmond being an overlap of NE-MA and SE regional services so people can ride there from say Charlotte then transfer to continue onto D.C.
For more local rail, cities (or states like how NJ does it) can promote commuter rail as an easy way to access the city from the suburbs and exurbs. You can drive or take a bus to the station then sit on the train with not a care in the world for the rest of the trip. It saves you fuel, the time to look for parking, the task of driving (in which you are liable for anything that happens unlike just sitting on a train), and can be faster if during rush hour.
