Amtrak's high speed rail network was first tested on the Northeast Corridor and other parts of the US when the German ICE train sets came to visit America in the 90's. Amtrak's next-gen train sets are sort of a hybrid between a few different train sets, to quote the Armchair Urbanist "Amtrak liked the capabilities of the X2000, but they did not like the cost. They liked the dual power cars of the ICE, but didn't like the lack of tilting abilities." In 2025, the NEC now has a really nice high speed line. (And it would be nice if it would expand further)