Prior to RFD, farm families traveled miles to the post office to pick-up their mail, all the while paying the same rates as those living in towns and urban areas. During the service's early years, the carrier postmarked the items.
For decades Congress had been reluctant to institute free rural delivery, seeing the nation as too large for such a service and predicting financial disaster. RFD became an official part of the U.S. Postal Service in 1902. (Source)