Some 3% of the population are Afro-Costa Ricans; most descend from Jamaican immigrants who worked in the construction of that railway. U. S. convicts, Italians and Chinese immigrants also participated in the construction project. In exchange for completing the railroad, the Costa Rican government granted Minor C. Keith large tracts of land and a lease on the train route, which he used to produce bananas and export them to the United States. As a result, bananas came to rival coffee as the principal Costa Rican export, while foreign-owned corporations (including the United Fruit Company later) began to hold a major role in the national economy and eventually became a symbol of the exploitative export economy. The major labor dispute between the peasants and the United Fruit Company (The Great Banana Strike) was a major event in the country's history and was an important step that would eventually lead to the formation of effective Trade unions in Costa Rica, as the company was required to sign a collective agreement with its workers in 1938.