posted in various California locales. First I remember is at the I-10 rest stop just east of Redlands, on the way to Morongo. It is in a hillside with a dry creek nearby and apparently the snakes like that terrain.

More recently - I have seen such signs posted in the parking lot at Harrah's Ione Casino. I guess not all the snakes are inside the casino!

No signs were posted at Montana De Oro State Park Beach near San Luis Obispo back in 1974 when I almost stepped on a large rattler sunning himself on a sand dune. Snakes at the beach? Yep!