Element 95, americium, was discovered after element 96, but only just. Seaborg (see element 106), James, Morgan and Ghiorso share credit for the synthesis in 1944. Since the element is similar to europium (and below it in the periodic table) it seemed sensible to name element 105 for the American continent.
Americium-241 is the isotope first produced and is manufactured today in kilogram quantities for use in high-precision measuring devices and some home smoke detectors. All isotopes of the metal are radioactive, the longest half-life being about 7400 years.
Stephen R. Marsden (ChemTopics)