Since 1847, Liberia operated as an independent state with a constitutional system modeled on that of the United States. For a long portion of its history, its government was dominated by Americo-Liberians, a group of freed slaves and their descendants from the United States that first arrived in Liberia in 1822 in a colony founded by the American Colonization Society. After the death of the long-serving president, William Tubman, in 1971, William Tolbert, Jr., became president. Tolbert's administration, like his predecessor's, was characterized by political suppression and a government dominated by the executive. In 1979, civil discord rose to an all-time high due to a 50% increase in rice prices that resulted in the deaths of dozens of Liberians. In addition to an overall lack of development and a stagnant economy, this unrest precipitated the 1980 Liberian coup d'état that would lead to the creation of the PRC.