Here is a story of a rider and a horse that were saved in a Dakota County Park in Minnesota, because of those blue USNG signs.
Here is an excerpt from the story with a link to the rest of the article:
The caller reported his location using an eight-digit number found on a nearby trail post. First responders located him quickly and saved the horse, said Randy Knippel, geographic information system manager for Dakota County.
For Knippel, it’s a success story demonstrating the value of emergency location markers, a system he’s encouraged county parks to implement.