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In Europe, travelers can buy a special rail pass that gives them unlimited train rides for a month. And some airlines offer tickets where a list of destinations is chosen in advance, but the flight dates are flexible and can be chosen on short notice.
Is there anything similar for traveling around the US by bus or train? Greyhound used to offer something like it, called the "Discovery Pass," but it seems to have been discontinued. And Amtrak only seems to offer unlimited passes on specific short routes, mainly targeting commuters.