A historic U.S. Airmail concrete arrow located in Skull Valley. This was used to mark the way for pilots during the 1920s. There would have been a tower with a lighted beacon for navigation at night.
This one is designated SALT LK AWY BN 59 and is located at the north end of Skull Valley, Tooele County, just off of Exit 77 on I-80.
Here is a good Google Map to find more.