Came across this collection of license plates by state, from the late '60s through today.
The designs were simple and functional when status striving was falling, and turned toward show-off-y and bragging styles once the striver impulse set in during the '80s.
There's still variation in the timing across the states, though, with the Plains and Mountain states tending to adopt striver plates as early as the '70s. Partly it's an effort to distinguish themselves to the rest of the nation that regards them as indistinct Flyover Country. But it's also a reflection of their Frontier inclination toward novelty and razzle-dazzle rather than tradition and simplicity.
In fairness, fancy plates also reflects the difference between wealth-based striving vs. lifestyle striving. The least pretentious plates are actually found in the most viciously competitive lands, along the Bos-Wash corridor. There, regional status contests focus on displays of power and wealth -- our state has more Fortune 500 companies than yours, more media control, more political control. We don't need to advertise how powerful our state is on our license plates, since wealth and power speak for themselves.
Out West, license plates serve as tourist brochures, with one or more advertising slogans, a claim to fame, gaudier typefaces, and scenic depictions of what makes us awesome. In Utah, it's "Life elevated," home to the "greatest snow on Earth".
The Midwest, Appalachia, and the South stayed unpretentious for a longer period, and didn't adopt brochure plates until the '90s and 2000s.
The less elite parts of New England like Maine and New Hampshire, beyond Greater Boston, have adopted brochure plates as well.
California has kept relatively simple plates, akin to the power centers of the East Coast.
The overly encrusted look and the whiff of desperation must be starting to grate on the nerves by now, as "retro" simplified plates have popped up here and there (Texas, Montana). Who knows if they'll catch on as options, or become standardized as the base plate, but it's a hopeful development that was not out there in the 2000s.
The online collection also has Canadian and Mexican plates to browse through. Overall, Canada has simple plates like the Midwestern US, except for gaudy brochure plates along the Atlantic coast, similar to the backwoods New England plates of Maine and New Hampshire.
Mexican plates are almost universally gaudy, outside of the power center around Mexico City.