From the Postal Museum | Precious Packages-America's Parcel Post Service
"...Parcel Post Service became available to Americans on January 1, 1913. Farm families, having made Rural Free Delivery a nation-wide success, were especially anxious to welcome the new service. Prior to 1913, farmers had to convey their produce to the nearest town large enough to support an express office, which added to the price of transporting their goods to the city. But with the combination of RFD and Parcel Post, package service was provided right from their mailbox. ..."
Reference: postalmuseum.si.edu
