Hausjärvi is a municipality of Finland. Its seat is in Oitti. It is located in the province of Southern Finland and is part of the Tavastia Proper region. The municipality has a population of () and covers an area of of which is water. The population density is . Geographically, and to some extent politically, Hausjärvi is characterized by its three population centres, Hikiä (population 1,055), Oitti (population 1,855) and Ryttylä (population 1,595). The administrative center of the municipality is Oitti, but politically there sometimes emerges debate on which centres should be developed and/or made targets of public investment. The municipality is unilingually Finnish. History The establishment of permanent settlement in what is now Hausjärvi is presumed to have begun around the 1300s by hunters from Janakkala. The first estates in Hausjärvi sprung up around river Puujoki, and the inhabitants were known to practice hunting as well as slash-and-burn agriculture. Metsäkansa - as Hausjärvi was known in the era around and preceding the Greater Wrath - was made a distinct chapel parish of the mother parish of Janakkala in 1611, which also prompted the construction of its first church in the same year. Hausjärvi was elevated to the status of an independent parish by imperial proclamation in 1855. The Helsinki–Hämeenlinna and Riihimäki–Saint Petersburg railways marked a turning point for the sparsely populated municipality. The villages of Hyvinkää and Riihimäki, in particular, benefited heavily from becoming junction stations, and they were granted independence from Hausjärvi as market towns in 1918 and 1922, respectively. Later on, the village of Oitti, aided by its station on the Riihimäki–Lahti section, became the administrative center of the remaining parts of Hausjärvi. Geography The first Salpausselkä cuts through Hausjärvi from the southeast to the northeast. It manifests as a wide ridge in the southeast, and reaches a height of above sea level around lake Erkylänjärvi. Progressing towards the east, the ridge narrows down around Hikiä and splits in two around Oitti. The southern branch is known as Patastenmäki and reaches above sea level. The ridge then decreases in height as it reaches the municipality of Kärkölä in the east. In addition, a fragmented esker reaches from Hikiä to the parish village, Lavinto, Turkhauta and Hämeenlinna, where it is known as Hattelmalanharju. The most notable river in Hausjärvi is the Puujoki, into which drains lake Pääjärvi in Lammi and Hämeenkoski. Villages In 1967, Hausjärvi had 19 legally