Jämsä is a Finnish city located in the southern part of the province of Central Finland on the western shore of Lake Päijänne, Finland's second largest lake. The city is home to 20,120 people (30 June 2020) and covers an area of ​​1,823.91 km², of which 252.54 km² are water bodies (1 January 2020). The population density is 12.8 inhabitants / km².

Jämsä is the only medieval parish in its province. The municipality of Jämsä was founded in 1866, it acquired commercial rights in 1969, and it became a city in 1977. The neighboring municipalities of Jämsä are Juupajoki, Jyväskylä, Keuruu, Kuhmoinen, Luhanka, Mänttä-Vilppula, Orivesi and Petäjävesi.

The municipality of Kuorevesi was annexed to Jämsä in 2001. From the beginning of 2007, the eastern parts of Längelmäki, which belongs to the province of Pirkanmaa, were connected to Jämsä and the western parts to the city of Orivesi. About 2/3 of Längelmäki's residents lived in the area connected to Jämsä. The association had no effect on the number of MPs elected from the Pirkanmaa and Central Finland constituencies in the 2007 parliamentary elections. The municipal associations continued in 2009, when Jämsä and Jämsänkoski merged. At the beginning of 1969, the municipality of Koskenpää was connected to Jämsänkoski. The new city was named Jämsä and the coat of arms was Jämsänkoski.

After World War II, settlers from Valkjärvi and Kivennava were stationed in Jämsä.

Jämsä's dialectal name is Jämpsä.


Etymology of the name
The origin of Jämsä propri is not entirely certain. Janne Saarikivi has suggested that the name Jämsä is related to a proverb that has evolved from the Northern Sámi verb jápmit (die). The present-day Sámi languages have several place names derived from the appellative jámeš (deceased). Max Wassmer once suggested that the name Jämsä is related to the shape and flow pattern of the Jämsä River. According to him, the river got its name before the permanent residents of the Jämsä region from the way the river flow consumes the shores. The name may also be based on an ancient verb meaning eating, biting, or caving, from which a appellative for spinning has since been derived. In dialects, this word is Jämsä, jämpsä or jämäs (a trough-bladed and branched trough intended for leveling the inner surface of wooden containers). There is a verb to crumble in the grass (cleans the inside of bundle dishes with crumbs).