Business enterprise at Jämsänkoski rapids began at the end of the 18th century. The first entrepreneurs came from other regions and set up a sawmill at Hovilanhaara. The pulp mill established almost a century later was already a part of the boom period of Finnish chemical forest industry.

Operation of the mill met with ups and downs, depending on trends prevalent in the world economy. The small pulp mill in Central Finland had to learn the hard way and pay its dues. The first company ended in bankruptcy, but after that the operation was extended to paper production and manufacture of mechanical pulp. Professional and able company directors moved to Jämsänkoski and the results started to show improvement. Raising of the degree of processing brought returns to shareholders, too.

The biggest leap in industrial operation took place when Jämsänkoski merged with United Paper Mills Ltd in 1920. Jämsänkoski experienced a period of two strong managing directors. During the General's period in the 1920s and 30s, Rudolf Walden was at the helm of the company. In 1940, Juuso Walden stepped into his shoes, and his colourful period of managing directorship to the end of the 1960s is still well remembered by many locals.

In common with other Finnish paper companies, United Paper Mills experienced changes in forest industry in the 1970s. In the beginning of the 1980s, pulp production at Jämsänkoski ended and thermomechanical pulp became the main raw material of paper. The 1980s remained in history as the decade of company mergers. In the case of United, it meant establishment of UPM-Kymmene Oy after various stages, in 1996. At its inception, the new company was Europe's largest forest industry company in terms of turnover.