For example, this Traditional in Idaho has only been found once in all its 20 years.
The website uses a points system based on cache age and number of finds to determine a cache's score
That's an interesting site.
Several of the long-unfound caches in my area appear to be gone, and the listings in need of retirement. They were placed along riverbanks and likely washed away or were covered by mud years ago.
My anxious ass would have the fear that the reason why a particular cache has rarely been visited is because people that visit get kidnapped/murdered before they record the cache.
I was thinking most of the caches are just missing but damn this is advanced worrying
Is there a reason it's US only? API limitation or just scope chosen by the developer.
Think it is a choice by the developer.
But Project-GC has similar tools here https://project-gc.com/Statistics/LonelyCaches and here https://project-gc.com/Statistics/DaysSinceLastFound. Maybe not as nicely presented as the site in the OP, but can be used for all the countries.
Geocaching is a worldwide scavenger hunt that uses a GPS or phone app with GPS. There are over 3 million active caches around the world. Some are as small as a dime, others are big enough to walk into, all of them provide a unique adventure. We invite you to share your stories, photos, and experiences!