William J. Gicker Jr., the manager of stamp development at the Postal Service, said the “warm and engaging” way Mr. Rogers communicated made him an appropriate choice.

“There are certain things you can’t do electronically,” he said in an interview. “If someone has done a kindness, a personal note is still far more valuable than shooting off an email or text. There is still a place for the written letter.”

The postage stamp is the latest cultural emblem of the enduring appeal of Mr. Rogers and his show, which is marking the 50th anniversary of its American premiere. Last month, TriStar Pictures announced that Tom Hanks would play Mr. Rogers in the biopic “You Are My Friend,” about his friendship with a journalist.

Mr. Rogers has inspired books and documentaries, been spoofed on “Saturday Night Live” and even inspired a category on “Jeopardy!”

His persona resonated off screen as well, such as when he testified before a Senate subcommittee to push for…

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