Carey Winfrey (Courtesy of Smithsonian)

One of the few low-turnover jobs in Washington journalism is about to turn over. Smithsonian magazine editor Carey Winfrey — only the third editor in the monthly’s 40-year history — will retire in September. No successor is waiting in the wings yet, but Winfrey, 70, told us that after 10 years at the top, it’s time for someone new. With a circulation of two million, the magazine is “doing well,” he said; contrary to popular assumption, it helps support the museums, not vice versa. A vet­eran of Time, People and the New York Times, Winfrey said he’s still pondering his next step: Something, he said, “between writing the Great American Novel, and a lot of e-mails.”