In July, Lockheed Martin completed the build of NASA’s X-59 test aircraft, which is designed to turn sonic booms into mere thumps, in the hope of making overland supersonic flight a possibility. Ground tests and a first test flight are planned for later in the year. NASA aims to have enough data to hand over to US regulators in 2027.
It would still take you 2-3 days, assuming normal operation with stops along the way. If the fastest train that exists on the planet right now ran from NYC to L.A. and was able to go from 0 to top speed instantly, and maintain that speed the entire trip, it would still take 10 hours to get there. Trains don’t operate that way though, so realistically it’s 3 days worth of travel. It’s almost 3000 miles to cross the USA.