After the mid-19th century, the economy was based on coffee growing. As the world market for indigo withered away, the economy prospered or suffered as the world coffee price fluctuated. The enormous profits that coffee yielded as a monoculture export served as an impetus for the concentration of land into the hands of an oligarchy of just a few families. Throughout the last half of the 19th century, a succession of presidents from the ranks of the Salvadoran oligarchy, nominally both conservative and liberal, generally agreed on the promotion of coffee as the predominant cash crop, the development of infrastructure (railroads and port facilities) primarily in support of the coffee trade, the elimination of communal landholdings to facilitate further coffee production, the passage of anti-vagrancy laws to ensure that displaced campesinos and other rural residents provided sufficient labour for the coffee fincas (plantations), and the suppression of rural discontent. In 1912, the national guard was created as a rural police force.