Circulation data for U.S. newspapers and magazines is compiled by the Audit Bureau of Circulations (ABC) and published in FAS-FAX Reports. Current circulation data is available in ABC's eCirc database, and considerable data from the Reports is posted on ABC's Free Reports page. For more information, call the ABC Service Department (847-879-8267. Note: There is a U.K. equivalent with similar data on its Web site (www.abc.org.uk).
Circulation information is also available in the Standard Periodical Directory and the National Directory of Magazines, both by Oxbridge Communications.
Finally, I have been told that U.S. newspapers and magazines must publish their circulation figures at least annually. Many do, often in a box in one of the first or last few pages of an issue. If you can't locate that easily, you could call the publisher and ask for help.
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