This is an evaluation of where Interzone, now twenty-eight years old and well past two hundred issues published, fits into the SF canon.
How does one evaluate a magazine? Is it the circulation? How many awards it's won? Or how many memorable stories and articles that it carries? Or is it the length of its lifespan?
Circulation Figures
Circulation figures are pretty much irrelevant -- Campbell's Astounding never matched the sales figures of Amazing during the infamous 'Shaver mysteries,' (a 1940s precursor to von Daniken which was used by the intelligentsia to lambast SF readers). Analog's sales peak in 1983/4 came long after Campbell had changed the magazine's name, but also after its influence had waned.
Interzone's circulation has traditionally been hampered by a variety of distribution problems, including the sheer cost of getting physical copies to the US, which provides the overwhelming majority of subscribers to the other magazines. Hopefully for the magazine's continued survival, with the spread of e-books and magazines, this is a situation that may well change.
Awards
Interzone has won the British Fantasy Award and the Hugo Award for Best semi-prozine, a classification decided by its pay rates, circulation and number of staff. 2010 marked the 25th consecutive year that the magazine has been nominated for this particular award.
Golden Age SF
Readers often talk about Campbell's 'Golden Age,' which ran from 1939 to about 1950, and when they do, it's to talk about the number of stories that the magazine ran during that period, which through repeated reprinting have entered SF's history as 'classics.' Editor and writer Terry Carr once observed that 'the Golden Age of SF is twelve,' reflecting on the subjective nature of picking 'classics.' Nonetheless, with the gradual spread of award ballots and Year's Best lists, there are now ways of providing some sort of objective criteria, using quantitative as well as anecdotal measures.
On average, Interzone has had three stories selected for inclusion each year over the last decade (or the same story may appear in three different selections, as was the case with Bruce Sterling's 'Black Swan'!), and this year the magazine became one of a select club of eleven magazines -including Amazing Stories and Playboy- to have had one of its stories win a Nebula Award. That was at its fifth attempt since 1987. A fifth story has also earned a Hugo nomination, so it will be interesting to see whether Eugie Foster can win both awards.
Longevity
Awards, circulation figures, the number of memorable stories, all play a part -- in generating a snapshot of a particular time. What about longevity, though? Awards and Year's Best are snapshots of one particular year, that longevity is an equally valid measure, especially given that producing a magazine is a vastly time-consuming and expensive process for anyone but a specialized professional publisher. If enough fans are prepared to buy copies of a magazine, or the editors and publishers can find ways of covering the costs, then the magazine will persist -- only when circulation drops below critical mass will it die. But the history of SF is littered with magazines, Campbell's Unknown, Venture, Science Fiction Age, and most recently Sci.Fiction, that shone brightly for a while, then guttered and died, too quickly.
At the moment Interzone is the eighth longest running magazine in SF history, having appeared in every year from 1982 to date, a span of twenty-eight years. New Worlds appeared in thirty of thirty-one years from 1946 to 1976 inclusive (this discounts the Garnett issues as aside from the name, there was no overlap with the magazine). If Interzone maintains its schedule for another seventeen issues, it will pass New Worlds in May 2013, and also pass Galaxy into sixth place. That magazine also ran for thirty years, and produced two-hundred and forty-five issues.
Competitors
That's about as high a high a ranking as the magazine is likely to achieve in at least the next decade, unless Asimov's folds. The Big Five of SF magazines are (mostly) so much older and have published so many more issues that they're unlikely to be caught.
Those Big Five, in terms of longevity and issues are:
5. Asimov's: 33 years; 1977 - 2010; 415 issues (at July 2010)
4. F & SF : 61 years; 1949 - 2010; 678 issues
3. Amazing Stories*: 79 years; 1926 - 2005; 611 issues
2. Astounding / Analog: 80 years; 1930 - 2010; 939 issues
1. Weird Tales: ** 87 years; 1923 - 2010; 355 issues
(source: http://www.isfdb.org)
Nonetheless, Interzone is punching well above its weight for the resources at its disposal (compared to say Dell Magazines, who publish Analog, Asimov's and EQMM) by publishing exciting new authors on a regular basis, providing visuals equaled by none in the genre and intelligent, literate reviews, but is also building a long tradition of excellence stretching back for most of its twenty-eight years.
Long may that continue.
Notes
* Amazing appeared every year until 1996, missed the following year, but limped on until 2000. It then disappeared until 2004, when it ran for four last issues.
** Weird Tales ran from 1923 - 54, 1973-4, 1984-5, 1988 - 94, and 1998 to date. With (mostly) bi-monthly or even quarterly editions, the issue count is surprisingly low, until one considers that the issue count covers only 52 years of its 87 year history.