The remaining population, human, mutant, and alien alike, have settled into small communities, tribes, roving bands, and villages. Each with its own form of leadership, government, or lack thereof.
Roads that once were gridlocked with vehicles are now rusty, overgrown, car graveyards still occupied with the skeletal drivers.
Gasoline is not exactly rare, nor are parts for vehicles, but the know-how to repair and keep them running is scarce. Many vehicles run on hydrogen or other form of energy batteries.
There are an abundance of weapons and ammo as well, though most weapon shops have long since been scavenged. The same is sadly true of food and medical supplies as well.
High Tech relics can often be found in military installations, research centers,and crashed ships that have not been already stripped. Although even most of the aliens that were originally aboard those ships have already passed, knowledge is passed on to a few of the worlds first generation since the Terraforming Event.