At the end of the Golden Age the great transit networks collapsed along with all the other trappings of civilization. Three hundred years later they mostly remain that way. Most people on the planet are born, live, and die within a ten to twenty mile circle. While they live, the fastest thing most of them will ever have access to is a horse or similar mount. Those who have access to anything so modern as an ATV or a hoverbike are in the minority.
Even so, long range travel is largely a thing of the past. Moving overland even with modern conveniences is incredibly dangerous and in North America and most other places the road network has fared poorly over the last few hundred years. Even were it in better shape, hostile encounters are a fact of life everywhere on the planet and one bad break can leave a person stranded hundreds of miles from even the most rudimentary civilization even if he’s lucky enough to survive.
In the air and on the sea it’s no better. As many monsters swim or fly as walk and the great airplanes and ships of yesteryear are largely gone. Few have the technology anymore to build large modern ships and practically no one makes aircraft but for military purposes with the exception of techno wizards who are largely limited to using their conveyances in areas with lots of ley lines. Magic is much quicker and in many ways a safer means of reaching far destinations and has the advantage of being more versatile in that a skilled or particularly bold shifter or rift diver can reach other worlds or dimensions, not just distant parts of Rifts Earth. This too has its pitfalls though, as teleportation and rifts travel are just as likely to go places that no sane person wants to be – and that’s if they go where the mage intended them.
Of course long range travel does happen. People get from point A to point B even when point B is across an ocean. It’s simply that these tend to be well resourced, well equipped people. And even then they often have a hard time of it. On the whole the situation is analogous to travel in the age of sail. You can do it, but it’s uncommon, expensive, dangerous and largely the province of governments and wealthy explorers.
Of course those explorers of yesteryear never got stuck in a hell realm after being swallowed by a rift. So there’s that.