|— Municipality —|
|• Total||2,077.73 km2 (802.22 sq mi)|
|• Land||1,427.89 km2 (551.31 sq mi)|
|• Water||649.84 km2 (250.90 sq mi)|
|Area as of January 1, 2010.|
|Population (June 30, 2012)|
|• Density||25/km2 ( 64/sq mi)|
|Time zone||CET (UTC+1)|
|• Summer (DST)||CEST (UTC+2)|
|ISO 3166 code||SE|
The municipality was created in 1971 with the amalgamation of the City of Nyköping and a great number of other municipalities. It was split up in three parts in 1992, when Gnesta Municipality and Trosa Municipality were created.
The municipality has 3,000 companies but more than 50% are sole traders. Only 80 have more than 25 employees; of those 33 have more than 50 employees.
A former military airfield in the municipality serves now as a civilian airport called Stockholm-Skavsta Airport.
Nyköping is the site of the prestigious Nyköpings Gymnasium, consisting of two schools: Gripen and Tessin as well as a smaller one located within the Stockholm-Skavsta Airport. Tessin being a high school noted for the strength of its curricula in humanities, arts, and social studies. Although Gripen has a higher admission credit needed as it has the more desirable program (the science program). The highest admission score to Tessin was for the year 2011-12 175 points and for the same year the science program on Gripen needed a score of 225, keep in mind these scores could have decreased during the admission period as people might have gotten in as reserves to one of their higher choices.
Tourist attraction 
Nyköpinghus, a medieval castle, draws many thousands of tourists yearly, especially for its summer outdoor play, Nyköpings gästabud , dramatizing 14th-century events in which king Birger Magnusson and Queen Märta invited his two brothers Valdemar and Erik to the castle, ostensibly for a banquet of reconciliation after a civil war in which Valdemar and Erik had once imprisoned Birger. During the banquet at Nyköpingshus, Birger arrested Valdemar and Erik and committed them to the dungeon, where, according to legend, they starved to death. Shortly thereafter supporters of Valdemar and Erik forced Birger and Märta to flee to Denmark.
Sister cities 
The "Nordic sisters" were created following World War II. In chronological order:
- Nykøbing Falster, Denmark (1947)
- Iisalmi, Finland
- Notodden, Norway
- Lauf an der Pegnitz, Germany
- Salacgrīva, Latvia
- Vyborg, Russia
- Nyköping Municipality - Official site