Which is the rarest US license plate in a collectors point of view?

The rarest U.S. license plate from a collector's perspective is often considered to be the 1903 Massachusetts plate, known as the "First Plate." Only a few are known to exist, and its historical significance as one of the earliest issued plates makes it highly sought after. Other rare plates include the 1914 California "Black Plate" and various early 20th-century plates from states like New York and New Jersey. Collectors often value rarity, condition, and historical context when assessing a plate's worth.