Central Post Office
The city was originally named Marshfield. In 1916, the name was changed to Declo. The Central Post Office told the community to choose another name not to exceed five letters. the last initials of the first five men to enter the post office were recorded: August Detlef, George Eldredge, Hyrum S. Lewis, James Cooley and Carl Osterhout. The Central Post Office said they preferred Declo instead of Delco, and such it was named. https://magicvalley.com/blogs/city-watch/blog-how-cassia-county-towns-got-their-names/article_069409f4-fe47-11e3-a65c-0019bb2963f4.html