In the two centuries which had elapsed since Vance Garamond's discovery of Orbitsville the circumstance of mankind's existence had completely changed. One of the most quoted statistics connected with the Big O was that it provided prime-quality living space equivalent to five billion Earths, but even more significant was the fact that it had enough room to accommodate every intelligent creature in the galaxy. For the first time in history there had been little or no brake on human expansion, and the migrations had begun immediately.

Earth's technology and industry had become totally absorbed in the last great challenge, that of transporting an entire planetary population across hundreds of light years to its ultimate home. It had been a venture only made feasible by two factors — the old world's declining birth rate, and the irresistibleness of Orbitsville's call. Every nation, every statelet, every political party, power group, religion, sect, church, family, individual could have the equivalent of a virgin world in which to pursue ideals and dreams. Governments had been slower to adapt to the new era man peoples, but statesmen and politicians — faced with the prospect of strutting empty stages — had eventually been persuaded that their duties lay elsewhere.

Each migratory government had, by UN agreement, retained responsibility for law and order in its historic territories, but time and distance had had their inevitable effect. Interest had declined, costs had increased, and many totalitarian states had in the end opted for the clean break solution, with compulsory migration of all subjects. Enforced migration to Orbitsville had not been possible in democratic countries, but that had not prevented governments — anxious to shake the clogging dust of the past from their feet — from using every conceivable inducement and pressure. More and more towns and cities had crumbled, ever larger areas of rural land had become overgrown, as the ordinary people had succumbed to the lure of the golden journey, the free trip to the Big O.