South Dakota Alphanumeric challenge.

Yes, the "unknown/mystery" cache is at the posted coordinates. Ahha, BUT in order to claim this as a find you must first qualify by finding at least one cache each with names that start with numerals 0-9 and letters A-Z. That's 36 finds. They all must be caches located in South Dakota.

Post a list by way of bookmarks or database or the MyGeocaching Alphanumeric Challenge (modified to show SD) or any other method that shows you found the needed caches.

Some clarifications: a cache name that starts with "The" counts for T and "A" counts for A. I will accept the number sign (also called pound sign) "#" if it precedes the numeral.

Yes, retroactive caches and caches placed after this challenge's publishing count. 

Most of the needed caches can be found within a couple dozen miles of the final location (A-Z is possible just in Yankton County).