Covered Bridge Post Office?

In case you haven't figured it out by now, I collect postcards. Sometimes, that can send me off on a tangent. While perusing my favorite hunting ground for Arkansas postcards, I found a real oddity and two postcards on the subject.

Back of the postcard 
 This is on beautiful Lake Ouachita, where there are 30,000 acres of water. Lake Ouachita also furnished some of the finest year-round fishing in the U.S.
It was postmarked Sep. 17, 1964

Really strange, right? A covered bridge post office! As you can see from this postcard, it wasn't very big.

I did some research on the Web. Crystal Springs is an unincorporated community located in Garland County, not far from Hot Springs and Lake Ouachita. 

Back of the postcard 
 The water is fed by springs under this building. We are within two miles of beautiful Lake Ouachita where fishing is good the year round. We have a Church of Christ which welcomes you. 

The building is no longer a post office but a private residence. As far as I can tell, it was a post office only for a short time. 

For current photos of the post office, you can go to http://www.dalejtravis.com/bridge/arkansas/htm/04026a.htm