the Allaine itself, it includes the watershed of the Creux-Genat River, that flows down from the peaks of La Banné () and La Perche (). In the north, the municipality includes the hills and forests of the Petit Fahy () und Grand Fahy (). The highest point in the municipality is the ridge that divides it from the municipality of Bure at . Coat of arms The blazon of the municipal coat of arms is Argent, a Boar salient Sable. Demographics Porrentruy has a population () of . , 16.4% of the population are resident foreign nationals. Over the last 10 years (2000–2010) the population has changed at a rate of -0.9%. Migration accounted for 0.3%, while births and deaths accounted for -2.9%. Most of the population () speaks French (6,046 or 89.5%) as their first language, German is the second most common (191 or 2.8%) and Italian is the third (147 or 2.2%). There are 2 people who speak Romansh. , the population was 48.5% male and 51.5% female. The population was made up of 2,655 Swiss men (39.9% of the population) and 573 (8.6%) non-Swiss men. There were 2,895 Swiss women (43.5%) and 533 (8.0%) non-Swiss women. Of the population in the municipality, 2,201 or about 32.6% were born in Porrentruy and lived there in 2000. There were 2,066 or 30.6% who were born in the same canton, while 812 or 12.0% were born somewhere else in Switzerland, and 1,361 or 20.2% were born outside of Switzerland. , children and teenagers (0–19 years old) make up 22% of the population, while adults (20–64 years old) make up 59.5% and seniors (over 64 years old) make up 18.5%. , there were 2,770 people who were single and never married in the municipality. There were 3,031 married individuals, 498 widows or widowers and 454 individuals who are divorced. , there were 3,022 private households in the municipality, and an average of 2.1 persons per household. There were 1,261 households that consist of only one person and 152 households with five or more people. , a total of 2,921 apartments (84.5% of the total) were permanently occupied, while 259 apartments (7.5%) were seasonally occupied and 278 apartments (8.0%) were empty. , the construction rate of new housing units was 1.7 new units per 1000 residents. The vacancy rate for the municipality, , was 2.25%. The historical population is given in the