The 1879 Post Office Act created the four categories of mailable matter used today and, in part, signalled the emergence of the modern mass circulated magazine. Between 1863 and 1879, Congress liberalized the terms on which regular periodicals could use the mails and put newspapers and magazines on the same footing. Requiring payment of postage at the office of mailing was the only setback publishers suffered, and the financial burden of that 1874 decision was offset by charging less postage, the forerunner of the bulk mailing rates. Some of the policymaking of this period can be seen as a marriage of interests between postal administrators and established publishers. Faced with chronic deficits, the post office sought to keep a new form of printed matter, the advertising circular, from passing through the mails at second-class rates. Little has changed in over a hundred years. Today, newspaper and magazine publishers intervene whenever the U.S. Postal Service considers rate changes that threaten to divert advertising from their pages to direct-mail circulars. These developments in the publishing industry and postal administration presaged more general national economic regulation, for recent scholarship suggests that much of the late nineteenth century trend toward federal intervention in the economy reflects intra industry struggles such as this. (SRT)