Geithus is the most typical industrial area in Modum. This is the home of Union-Geithus, Drammensriver Papermill, which is the largest private employer in the municipality of Modum. Geithus has a population of of about 2,200 and is one of the areas in the municipality where big investments are being made. Among other things, there are the long-term plans for a large sports park at Furumo. There are also more than enough industrial lots.