Mäntsälä () is a municipality in the province of Southern Finland, and is part of the Uusimaa region. It has a population of () and covers an area of of which is water. The population density is . The municipality is unilingually Finnish. Mäntsälä is one of three municipalities in the Uusimaa region that do not have a Swedish name; the others are Nurmijärvi and Askola. Mäntsälä lies about north of Helsinki, the capital of Finland. During the last few years, the population of Mäntsälä has been one of the most rapidly increasing in Finland. A new railway, the Kerava–Lahti railway line, was built between Kerava and Lahti with passenger traffic starting on 4 September 2006 from Mäntsälä railway station. Helsinki is about 40 minutes away, and Lahti even closer. Highway 4 (E75) connecting both cities passes through Mäntsälä. The coat of arms of Mäntsälä has its theme in the region's traditional livelihoods; the head of the moose refers to the hunting lands of the region, and the clovers symbolizes local agriculture. The coat of arms was designed by Olof Eriksson and approved by the Mäntsälä Municipal Council on 16 December 1950. The coat of arms was officially approved by the Ministry of the Interior on 20 February 1951. History Mäntsälä is considered to have been founded in 1585, when the community's first church was built. The current church was completed in 1866 after delay. The Crimean War affected also Mäntsälä: funds for building the church were spent on war efforts. All of the churches were located on Kirkonmäki ("Church Hill") at about the same spot. The first common school was founded in 1870 by way of a testament of clergyman Abraham Ehnroos. To his credit is the founding of a public library already in 1840. An intermediate school was not founded until 1945 with a high school following in 1954, previously facilities in Porvoo, Järvenpää and Helsinki were used. In 1854 the first town hall was built on Kirkonmäki. Today a museum is operating in the building, having also served as a morgue, school kitchen and lesson space, and a dormitory. It is deteriorating severely and the museum is only opened upon request. The second town hall was built in 1935, also on Kirkonmäki. It served until the completion of the present town hall in 1992. Now it houses an open college. There is a total of 15 manors