I&#x27;d vote for &quot;within 3 hours&quot;. 1 hour for travel time to airport, 1 hour for boarding (hand luggage only), 1 hour for flight. Meaning: up to 500 miles. Or: 1 hour to get to railway station, 15 minutes for boarding, 1h45m on a train (meaning anything from 100 miles -- USA -- to 300 miles -- Japan, Spain, France, Germany, etc).<p>Your next step up is 6 hours. Flight as above, plus one transfer (1 hour) and two more hours in the air, or 4 hours on one sector. So call it up to 2000 miles. Or by rail, between 500 miles (USA: DC to Boston by Acela) and 700 miles (Tokyo to Fukuoka by Shinkansen -- actually only 5 hours).<p>Longest options: I can get from Aberdeen (Scotland) to Wellington (New Zealand) in a little over 24 hours, and those are within a couple of hundred miles of being antipodal points on the globe.<p>To take much more than 48 hours you&#x27;d need at least one end point to be somewhere either in a war zone or at the wrong end of a thousand miles of dirt track -- Raqqa in Syria maybe, or somewhere in the arse end of the Congo or the Gobi Desert.