La Unión (Spanish pronunciation: [lawˈnjon]) is the easternmost department of El Salvador.

The department was created on June 22, 1865, and the city of La Unión was made its capital.

The Conchagua Temple was built in 1693 and it is one of tourist attractions of the department, as well as containing archeological ruins in Intipucá and Meanguera.

The most important agricultural products are coffee, grass, fruits, cocoa, oleaginous seeds, and sugar cane.

The manufacturing of palm and tortoiseshell products, panela, mangrove extract, and fish.