Liberia, the oldest independent Negro state in West Africa, has been struggling for survival ever since its foundation in 1822. Progress has been hampered by constant hostility between tile American Negroes whose families returned there in the early nineteenth century and the West Africans whose ancestors never left the continent. Though the two groups arc of the same race, they are divided by language and outlook and regard each other with deep suspicion, creating a conflict which was not foreseen by Liberia's founders. In addition, neighboring states, native tribes, disease, and poverty have made life dangerous and difficult. The government has tried desperately, through loans and a trickle of trade, to make ends meet. Anxiety about financial matters lessened somewhat when, in 1910, the United States accepted responsibility for Liberia's survival. However, not until Harvey Firestone, the American rubber magnate, decided that the United States must produce its own rubber-with Liberia as the site of the rubber plantations-did Liberia have much hope of paying its debts and balancing its budget. The rubber industry, founded in the 1920's, and the activity that followed it, brought both progress and profit to Liberia. Before that time Liberia had no roads, no mechanical transport, and few tools. Now Liberians feel that the country is being ruled by rubber. For this reason the recent discovery of iron ore is important. Liberian leaders are trying to moderate the power of the rubber industry and to establish the country's political and economic independence. The greatest problem of the Liberian government has been______.