Try asking a librarian. If you have access to a university a government documents librarian, or a business librarian would be very helpful. But a public librarian may be able to help too. Many librarians specialize in a certain area and business and government documents are two known areas. Sorry I couldn't actually answer your question.

Contact the personnel office at the Postal Service.

From the USPS site: Contract Delivery Service - Contracting Opportunities Contract Delivery Service is a contractual agreement between the U.S. Postal Service and an individual or company for the delivery and collection of mail. The typical service required at the local Post Office™ will involve sorting mail for the route, driving to the route, delivering mail to specified addresses, picking up collection mail, and returning to the Post Office. Each contract includes a delivery schedule, a complete route description, and a description of basic responsibilities. The contract route will operate six days per week, Monday through Saturday, and does not include holidays. The carrier is required to use their own vehicle for mail delivery service. The average route will require approximately four to eight hours per day to complete, depending on the size of the route. If you or your company are interested in receiving solicitations for Contract Delivery Service, please complete PS Form 5436, Mailing List Application - Mail Transportation Services and mail it to the contracting officer in your area. This information is available in the back of Publication 33, Mail Transportation Contract Guide at http://www.usps.com/cpim/ftp/pubs/pub33/welcome.htm.