Fourth class mail definitions

fourth-class mail

(from the article `postal system`) ...classes were established according to mail content: second-class consists of newspapers and magazines, third-class encompasses other printed ...
Found on http://www.britannica.com/eb/a-z/f/52

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Fourth-class mail

Parcel post, the U.S. Postal Service delivery of mail parcels weighing over 16 ounces.
Found on http://www.nmoa.org/Library/index.htm

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