I don't know whether it's only "an American thing" or not, but it's incredibly common (especially for kids) to use plastic bags over socks when they're going out for snow activity to keep their feet dry after snow works its way inside the boot and melts. Even when you're wearing wool socks in thermal boots, it's much warmer if you can keep water off your socks, and, by extension, your feet.
Bread bags were (and still are) the perfect size for this purpose for many feet. There's often a rubber band used around the leg to hold the top of the bag firmly against the leg (or pants). These days, plastic grocery bags would probably be more commonly used.
West Virginia (and Western Pennsylvania) sock waterproofing.