For a general overview of world and US license plate history, and to learn about this enjoyable hobby shared by thousands of enthusiasts around the globe, check out www.alpca.org , the official website of the Automobile License Plate Collectors Association. You will have to join this club in order to access their highly detailed archive of world license plates, but it is well worth it even if you only have a casual interest in the subject.
Several collectors maintain websites on their own personal collections or for presenting the history of their own state’s license plates. The complete listing of such sites can be found on the ALPCA website, once you join. Two sites in particular are outstanding in presenting information on very early pre-state plates: www.porcelainplates.net and www.chuckwestphalplates.com are especially worth a visit. The latter site contains a detailed history of New York State plates, and both include an abundance of high-quality photos.
For more photos, check out www.worldlicenseplates.com This site has photos from around the world, and for every state from the beginning to modern times.
Other websites that have good presentations include:
Arizona – www.azplates.com
District of Columbia – www.dcplates.net
Maryland – www.ricksplates.com
Washington – www.dol.wa.gov/vehicleregistration/sphistory.html