Fellow collector Michael Gulvin asks a question which many other collectors may have wondered: “On what day of the month did the Gentleman’s Magazine for August, 1776  become available? We have a time-line for the American newspapers, and we know that the London Chronicle printed the Declaration in its August 17th issue, but do we know the actual date the Gentleman’s Magazine printed the Declaration of Independence for its August issue?”
Magazines typically published very late in the month shown on the title/contents page. With the “London Chronicle ” publishing the Declaration of Independence in its August 17, 1776 issue, and presuming they had interest in publishing such a significant document as early as possible, it is presumed the Declaration was received in London very close to that date. Their previous issue was dated Aug. 15, so August 15-17 would be the presumed period when the document arrived in London. It is curious to note that the “London Gazette” never printed the Declaration of Independence.
Monthly publications are more difficult to pin down in terms of publication dates, however datelines of news reports found within offer great clues. The Historical Chronicle near the back of the August issue of the “Gentleman’s Magazine” has datelines beginning July 10 and the latest date mentioned is August 31, the very last day of the month. Obviously the magazine could not have printed prior to August 31, so the first day or two of September would be the presumed printing dates.
The same was true with American magazines as I recall the June, 1776 issue of “The Pennsylvania Magazine” had the very significant announcement that Congress had voted to approve the Declaration of Independence, with a dateline of July 2, 1776. Obviously that June issue was printed early the following month.