The Roots of the World and the Primal Currents are physical links between the Guardians and the rest of the world. They radiate out or somehow connect to each Guardian and their tributaries reach every corner of the planet. Most of these are inaccessible to mortals: either too far underground, high in the air, or deep in the oceans, but there are a few points where they can be found.
These points are the reason for the locations of the three Conduit Cities. A spike of pure tralaticon at the center of each city acts as the catalyst for drawing raw element energy from these sites and transforming it into electricity or trading the raw energy for the other two types with the other cities.
The Earth City is built around a deep hole that was dug as part of an ancient mining operation in the central region of the continent. What they were searching for has been lost, but they hit a segment of the Roots of the World. This root is a unique mixture of wood, granite, and tralaticon. No other Root is known to be this close to the surface.
The Air City towers into the northwestern sky and its highest structure is the top of the Conduit Plant at its center. The Primal Air current dips down low here. It is thought that ornithologists were the first to point to some strange properties of this area as they followed the migrations of birds around the continent.
The Water City straddles land and sea, with half of it beneath the waves and other half rising almost the heights of the Air City. Sailors long took note of the patterns of currents surrounding what was known pre-Apocalypse as Tralaticon Isle. The Water City is the only one that is not built protectively around its Conduit Plant, as the Primal Current is beyond the continental shelf on which the city rests. Instead, it is its own enclave where few are allowed to go and as well protected by natural inaccessibility as by the armed Census Office details.