La Unión is a city and commune located in Ranco Province within the Los Ríos Region of southern Chile. Situated approximately 40 kilometers north of Osorno and 80 kilometers southeast of Valdivia, it covers an area of 2,136.7 square kilometers. According to the 2012 census, the city had a population of 36,447 inhabitants, with 25,615 residing in the urban area.
The city's name derives from the confluence of the Llollelhue and Radimadi rivers, which meet in the commune. This geographic feature shaped the settlement's historical significance in the region.