| Official Name: | Arnö |
| Pushpin Map: | Sweden Södermanland#Sweden |
| Subdivision Type: | Country |
| Subdivision Name: | Sweden |
| Subdivision Type3: | Municipality |
| Subdivision Name3: | Nyköping Municipality |
| Subdivision Type2: | County |
| Subdivision Name2: | Södermanland County |
| Subdivision Type1: | Province |
| Subdivision Name1: | Södermanland |
| Area Footnotes: | [1] |
| Area Total Km2: | 2.10 |
| Population As Of: | 31 December 2010 |
| Population Total: | 3,871 |
| Population Density Km2: | 1843 |
| Timezone: | CET |
| Utc Offset: | +1 |
| Timezone Dst: | CEST |
| Utc Offset Dst: | +2 |
| Coordinates: | 58.7333°N 18°W |
Arnö is a locality situated in Nyköping Municipality, Södermanland County, Sweden with 3,871 inhabitants in 2010.
Arnö is situated on a peninsula on the south side of the bay, with Nyköping on the north side. Locally, Arnö is considered a part of main Nyköping, but is designated a locality due to the mile-long stretch between Nyköping and itself. The populated area was mainly built in the 1970s and has become a southern suburb of Nyköping, being in walking distance from the city. Expansion is planned eastwards towards the beach of Örstigsnäs. It is also located relatively near the town of Oxelösund, with its outer premises forming the municipal line.
| Year | % | Votes | V | S | MP | C | L | KD | M | SD | NyD | Left | Right | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1973[2] | 93.2 | 1,634 | 3.0 | 59.4 | 19.3 | 6.2 | 2.8 | 9.1 | 62.4 | 34.5 | ||||
| 1976[3] | 93.2 | 1,632 | 2.3 | 57.0 | 18.4 | 10.3 | 2.1 | 9.6 | 59.4 | 38.4 | ||||
| 1979[4] | 93.6 | 1,554 | 3.8 | 59.5 | 12.9 | 9.7 | 1.8 | 11.8 | 63.3 | 34.4 | ||||
| 1982[5] | 94.9 | 1,478 | 5.8 | 54.5 | 2.1 | 11.1 | 5.5 | 1.6 | 19.0 | 60.3 | 35.7 | |||
| 1985[6] | 94.2 | 1,640 | 5.7 | 52.2 | 1.3 | 6.7 | 15.5 | 18.4 | 57.9 | 40.6 | ||||
| 1988[7] | 92.1 | 1,653 | 6.2 | 49.6 | 5.1 | 7.3 | 14.1 | 1.9 | 15.1 | 61.0 | 36.4 | |||
| 1991[8] | 92.4 | 1,610 | 4.7 | 44.5 | 2.6 | 3.5 | 12.5 | 5.7 | 19.9 | 5.8 | 49.2 | 41.6 | ||
| 1994[9] | 92.0 | 1,860 | 7.3 | 54.1 | 4.8 | 3.1 | 9.1 | 3.1 | 17.0 | 0.6 | 66.3 | 32.3 | ||
| 1998[10] | 84.8 | 1,807 | 10.7 | 48.8 | 4.6 | 3.5 | 4.0 | 9.8 | 16.8 | 64.1 | 34.1 | |||
| 2002[11] | 82.4 | 1,959 | 9.0 | 53.4 | 4.3 | 3.5 | 10.4 | 8.6 | 9.9 | 0.4 | 66.8 | 32.3 | ||
| 2006[12] | 84.5 | 2,134 | 4.9 | 45.4 | 5.7 | 5.0 | 7.2 | 6.2 | 23.1 | 1.5 | 56.0 | 41.4 | ||
| 2010[13] | 87.3 | 2,277 | 4.8 | 40.8 | 9.8 | 3.2 | 7.5 | 4.4 | 25.0 | 3.5 | 55.4 | 40.1 | ||
| 2014[14] | 88.7 | 2,492 | 4.2 | 37.6 | 11.1 | 3.7 | 5.0 | 3.8 | 22.6 | 9.1 | 52.9 | 35.1 | ||
| 2018[15] | 85.2 | 2,772 | 6.9 | 36.8 | 4.9 | 8.6 | 4.9 | 5.5 | 21.3 | 10.2 | 57.3 | 41.9 |
The locality is divided into four areas. The northwestern area is named Herrhagen, which is a high-density residential area with mostly apartments. Långsätter is the largest area, located in between the circular road. It consists of villas as well as Tract housing. The northeastern area is named Kuggnäs after an old farm. The buildings in that area is mostly villas. The last area is Finntorp and Björkö, which together forms an area for manufacturing industries as well as commerce. The local prison of the Nyköping Municipality area is located here as well as the spare parts storage center of Saab Automobile.[16]