[2] It is a transboundary river shared by El Salvador, Guatemala and Honduras.

In Honduras, it flows through the Ocotepeque Department for 31.4 kilometres (19.5 mi), and crosses the border with El Salvador at the town of Citalá (14°22′19″N 89°12′45″W / 14.371857°N 89.212439°W / 14.371857; -89.212439) in the Chalatenango Department.

The river continues its course for another 360 kilometres (220 mi) in El Salvador, flowing in a generally southwards direction until it reaches the Pacific Ocean in the San Vicente Department.

[2][4] The river forms a small part of the international boundary between El Salvador and Honduras.

[1] 49% of El Salvador's territory is covered by the Lempa River basin,[1] and 77.5% of the Salvadoran population lives in cities, towns, and villages located within the basin territory, including the capital city of San Salvador.