Resource slots are the capacity of an area to support resource gatherers.
Each character gathering a resource uses up one resource slot. Once all the resource slots are occupied, no other characters can participate in resource gathering projects. Projects with no characters working on them do not take up a resource slot, and multiple characters working on the same gathering project still take up multiple resource slots.
Domesticated animals in packs will also take up resource slots.
Machines such as the potato harvester, the hematite drill, the oil derrick and many others can be used to increase the resource-gathering capacity of a location. Not only is resource gathering much faster while using these machines, but the use of these machines does not take up a resource slot, and the machines can be used even if all resource slots in a location are full.