It was billed as a land of promise — a place where free Black Americans could obtain more political rights and a better quality of life. Liberia did not receive its name until 1824, but the territory that became its capital city was purchased on Dec. 15, 1821. Almost exactly 200 years later, a Liberian historian has discovered that original purchase agreement — a document missing since 1835 that sheds light on the acquisition of the only U.S. colony in Africa.