Why isn't all the plot alloted for Industries getting used?

[ThatSaucepan]

Hi people, I installed this game a day ago, so idk much about the mechanics and stuff excuse me on that

For some reason, not all my industrial plots are being used and some built industries have no workers to them, why is this happening,

I have a small town with around 1.2k people living in it

[CommanderABab]

There might not be demand for much industry yet. Residential and commercial also must be filled out too. If you build a level TTT industrial with only level T residentials so far, it won't have available workers yet.

[Mendel]

You must pay attention to the demands. When a demand is high, you put zones. When a demand is low, you either ignore it or click on a building of that type to see the lowest happiness. Then you improve that happiness by building a building of that sort in the area.
Sometimes the demand goes up when you delete the type of RCI building and the demand goes down when you build too much of one RCI building.
RCI means Residential, Commercial and/or Industrial.