3500 kilometers / hour = 2174.79917 miles / hour
the japanese test track train has already reached speeds of over 603 kilometers / hour = 374.686829 miles / hour
of course u could make it much faster with a longer track & then much beyond a quarter mile u really need a evaccuated air tube because wind resistance starts to get really insane much beyond 400mph no matter how aerodymanic u make a train.
unless maybe u have some kinda energy field around the train like a warp bubble or something fancy.
Although maglev evacuated air tube trains are already run between the deep undeerground military bases around the world.
They exist i know they do we all know they do i even spoke 2 a furry once who had been taken into one several times becuase his farher was a reptilian shapeshifter.