Every year Scientific American produces a single-topic issue, and this time we're tackling the theme of origins: our September issue explores 57 innovations and insights that shape our world today. As an added bonus, we're presenting several related online-only features, including a weeklong posting of 10 additional origins stories as well as a special slide show.

And what better way to launch our special week of origins stories than with one about our own? Most people who have studied some science have heard of Scientific American , and even the young texting generation might be aware that it comes out in print once a month. But would you have guessed that Scientific American is the oldest continuously published magazine in the U.S.? Founded by inventor Rufus Porter, the first issue appeared as a large format newspaper in 1845—in fact, our 164th birthday happens next Friday, on August 28.

But The Scientific American, as Porter called it, hardly resembles today's publication (we've long since dropped the "the"). In the first issue, under the logo and scrolling leaves and flowers, a slogan reads: "The Advocate of Industry and Enterprise, and Journal of Mechanical and Other Improvements." The biweekly broadsheet focused mostly on patents and advice for inventors. After 10 months, Porter sold The Scientific American to Orson Desaix Munn and Alfred Ely Beach for $800—about $23,000 in today's dollars using the consumer price index (but about $5.65 million using the relative share of the gross domestic product as a measure).

The magazine began its modern incarnation after World War II. In 1948, Gerard Piel, Dennis Flanagan and Donald Miller purchased the publication from Munn & Company and founded Scientific American, Inc. In their quest to increase the immediacy, timeliness and authority of the magazine, they insisted that the majority of the articles be written by the people who actually did the work described—a unique distinction among consumer magazines.

Scientific American has greatly expanded its offerings since then. Besides the Web site, launched in 1996, we publish the bimonthly Scientific American Mind (begun in 2004) and have 15 international editions. We are now owned by Macmillan and are part of the Nature Publishing Group. You can read the magazine's full history here.