The Mano River is a river in west Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, it originates in the Guinea

Guinea

Guinea , officially the Republic of Guinea , is a country in West Africa. Formerly known as French Guinea , it is today sometimes called Guinea-Conakry to distinguish it from its neighbour Guinea-Bissau. Guinea is divided into eight administrative regions and subdivided into thirty-three prefectures...

 Highlands in Liberia

Liberia

Liberia , officially the Republic of Liberia, is a country in West Africa. It is bordered by Sierra Leone on the west, Guinea on the north and Côte d'Ivoire on the east. Liberia's coastline is composed of mostly mangrove forests while the more sparsely populated inland consists of forests that open...

 and forms part of the Liberia – Sierra Leone

Sierra Leone

Sierra Leone , officially the Republic of Sierra Leone, is a country in West Africa. It is bordered by Guinea to the north and east, Liberia to the southeast, and the Atlantic Ocean to the west and southwest. Sierra Leone covers a total area of and has an estimated population between 5.4 and 6.4...

 border.

The districts through which the river flows include the Parrot's Beak area of Guinea, Liberia's Lofa County

Lofa County

Lofa is a county in the northernmost portion of the West African nation of Liberia. One of 15 counties that comprise the first-level of administrative division in the nation, it has six districts. Voinjama serves as the capital with the area of the county measuring...

 and the Kono

Kono District

Kono District is a district in the Eastern Province of Sierra Leone. Its capital and largest city is Koidu Town. The other major towns in the district include Yengema, Tombodu, Motema, Jaiama-Nimokoro and Sewafe. Kono District is the largest diamond producer in Sierra Leone.The population of Kono...

 and Kailahun District

Kailahun District

Kailahun District is a district in the Eastern Province of Sierra Leone. Its capital and largest city is Kailahun. The other major towns in the district include Segbwema, Koindu, Pendembu and Daru. As of 2010, the district has a population of 395,957 ....

 of Sierra Leone. Diamond mining is a major industry in these areas. Control of the area's wealth and the instability of the national governments of all three countries led to a series of violent conflicts involving these districts in the 1990s (See Sierra Leone Civil War

Sierra Leone Civil War

The Sierra Leone Civil War began on 23 March 1991 when the Revolutionary United Front , with support from the special forces of Charles Taylor’s National Patriotic Front of Liberia , intervened in Sierra Leone in an attempt to overthrow the Joseph Momoh government...

, First Liberian Civil War, Second Liberian Civil War

Second Liberian Civil War

The Second Liberian Civil War began in 1999 when a rebel group backed by the government of neighbouring Guinea, the Liberians United for Reconciliation and Democracy , emerged in northern Liberia. In early 2003, a second rebel group, the Movement for Democracy in Liberia, emerged in the south, and...

).

Liberia and Sierra Leone founded the Mano River Union

Mano River Union

The Mano River Union is an international association established in 1973 between Liberia and Sierra Leone. In 1980, Guinea joined the union. The goal of the Union was to foster economic cooperation among the countries...

in 1973, Guinea joined in 1980. It was reactivated in 2004 as a customs and economic union; Côte d'Ivoire joined in 2008.