More information about Nigeria is available on the Nigeria Page and from other Department of State publications and other sources listed at the end of this fact sheet. U.S.-NIGERIA RELATIONS.The United States established diplomatic relations with Nigeria in 1960, following Nigeriaâs independence from the United Kingdom. From 1966-1999 Nigeria experienced a series of military coups, excluding the short-lived second republic between 1979-1983.ilateral Economic Relations. The United States is the largest foreign investor in Nigeria, with U.S. foreign direct investment concentrated largely in the petroleum/mining and wholesale trade sectors.