Why so many changes? Well, each state has its own rules, each state’s authorities have their own frequency of re-issuing plates and reasons for doing so. License plates were once re-issued every year, but now many states do so every five, seven, or ten years. Some states, like California, allow for “legacy” plates for historical purposes and nostalgia. Other states, like New York, phase old plates out slowly, over the span of several years, in which multiple designs of plates are acceptable.
Since materials are now more weather-resistant, the practice of re-issuing plates is far less frequent.
At least we — the wacky automobile drivers — don’t have to paint our initials on our cars ourselves anymore.
source: TitleMax.com