Over at the Infrastructurist they’ve made this useful zoomable map of various high-speed rail proposals including the official DOT corridors but also some other ideas:
It’s always important when talking about this stuff to be clear on exactly what’s meant. Incremental track upgrades that get your train up to 110 miles per hour are a lot cheaper than big investments in new 200+ mph “true” high-speed rail. But by the same token, a trip with a top speed of 220 mph will be a lot quicker than a trip with a top speed of 110 mph. We have ourselves a large and diverse country, so there are appropriate places for each strategy, but these are very different ideas.