The position of official bookseller was established (so far as I can tell*) in 2009, and for the first 5 years the position was filled by either Borders or Barnes & Noble. The national chains used their distribution networks to supply the thousands of books purchased at the festival, many of which are signed by the over 100 authors in attendance.
This year P&P will be making all those sales, with the support of Ingram. Over 15,000 copies have been ordered for the festival, which will be held on 30 August in the DC Convention Center (another first).
Politics & Prose co-owner Bradley Graham had pitched the idea of using an indie bookseller to FleishmanHillard , the pr firm which handled the bidding process. Graham noted that "One of the arguments I used was that independents are very involved in other major book festivals in other parts of the country, whether it’s Miami or Boston or Los Angeles or elsewhere." He added: "I thought that not only could we handle the job, but that it would be a signal, if an independent bookstore got the contract, that indies are still alive and well in this country and capable of handling large projects like this”.
This is going to be the largest event which Politics and Prose has participated in, but it's not their first book festival. The bookseller is also a partner with the Gaithersburg Book Festival, which draws about 20,000 people to southern Maryland in May.
Politics & Prose is an example of the resurgence of indie booksellers as the big box chains give way to Amazon. In addition to promoting local events, P&P also carries Kobo hardware, sells ebooks, and offers POD services via their Espresso Book Machine.
P.S. I can't find any sign that there was an official bookseller position before 2009. If I am wrong please let me know. I for one would like to know if P&P really is the first indie to hold the position.