Final answer:
Benjamin Banneker created the United States' first farmer's almanac, showcasing African-American intellectual capabilities during the era of slavery.
Step-by-step explanation:
Benjamin Banneker successfully created the first farmer's almanac in the United States. He was a self-taught mathematician, astronomer, and surveyor who used his vast knowledge to compile and publish the almanac, which included astronomical calculations, tide tables, and planting charts. Banneker's almanac was significant as it proved the intellectual capabilities and contributions of African Americans during a time when slavery was prevalent.