It spread Anglo-European culture across the nation and caused trade to flourish, but the story of the Chinese labourers who built the track has largely been forgotten.
Did Vikings find their way to a remote part of Oklahoma? Some in a small community believe so, thanks to controversial runic carvings found in the area.
A floating orange ball over the famed US route has puzzled travellers for 150 years. And while most agree that the so-called Hornet Spook Light exists, few agree on what causes it.