Michigan Trailer License Plate, 1964

Early state-issued license plates were made of porcelain-coated iron. Later, states stamped tin, steel, or even copper to make plates. During the Second World War several states used fiberboard. Plate colors varied and some states added symbols, mottoes, or other design elements. Today, states use reflective sheeting to coat a standard-sized aluminum blank which is then stamped and decorated.