When the Jämsänkoski pulp mill started up in 1888, the number of factory employees was 51. In 1894 the number had risen to 240, of whom 30 were women and 14 minors. By the mid-1910s the employee numbers had risen to 347 in total. The paper mills employed 149, the chemical pulp mill 83, grinding mills 66, collector section 22, and the repair workshop 27 persons. At the time, the factory also employed a nurse, a kindergarten manager and teacher. In 1912, the number of office staff and specialist professionals totalled 36. The total population of Jämsänkoski at the start of the 1900s was approximately 1,000. In the 1920s about a third of the 1,500 village inhabitants were employed at the factory.

The slump of the early 1930s did not impact on Jämsänkoski mills as a fall in staff numbers. Production continued under capacity, but additional work was provided by the new buildings and extensions to the factory. The depression was particularly hard for temporary employees and forest workers. During the war years, women were employed to replace the men who were at the front. During the interim peace, the foundation work for the factory rail track was under way at Jämsänkoski.

Shortage of labour soon turned into shortage of work, when jobs for the men returning from the front had to be found after the war. The company policy was that none of the permanent staff would be dismissed because of lack of work. By the end of the year 1946 there was already a shortage of manpower. New construction sections were treated as labour reserves, as their worker numbers could be easily reduced when necessary. Office staff were transferred from one company factory to another, as the need arose.

The employee numbers went up when the Kaipola mill was under construction, as most of the builders were the company's own people. Once the factory began operating, the total number of all United staff at the end of the 1950s was about 5,000 people. At the end of the following decade, United employed 1,100 people at Jämsänkoski and 950 in Jämsä. The proportion of women of the staff peaked at the end of the 1950s, varying at around 21 - 24 percent. The proportion of office staff of the total number of employees grew in the 1960s to 16 percent.