La Unio'n is a department of El Salvador. it is located in the eastern part of the country and its capital is La Unio'n. It covers a total of 2,074 km^(2) and has a population of 300,000.

The department was created on June 22, 1865 and the city of La Unio'n was made its capital. The Conchagua Temple was built in 1693 and it is one of tourist attractions of the department as well as some archeological ruins in Intipuca and Meanguera.