A lumber mill in Imperialism turns two units of timber into one unit of either lumber or paper with the help of two labor units.
The lumber can be:
- used in expanding mills, factories, or the transport network, or
- sent to the furniture factory, or
- sold
The paper can be:
- used in training civilians or untrained workers or trained workers, or
- sold
The mill starts at a size of 2 and can be expanded to 4 then 8 then additional increments of 8.