In 1982, I was 12 years old and living in West Virginia. I had been staying indoors for several days as I was sick with some childhood illness or other. When I finally re-emerged, the entire landscape had changed: Every tree, every surface was covered with cicadas. As an adult I might have been horrified, but as an elementary school kid I thought they were pretty cool!
I've moved several times since then, and now live in the cicada-free San Francisco Bay Area, so that was the first and possibly last time I've witnessed this particular phenomenon.