When people think of Fred Rogers, the long-time star of Mister Rogers’ Neighborhood, they usually picture him in one of his cardigan sweaters, which came in a variety of primary colors and spoke to the warm and fuzzy nature of his presence. Tom Hanks will shortly be seen in such a sweater, playing Rogers in November 22's A Beautiful Day in the Neighborhood.

In a new article for Smithsonian, Cristina Rouvalis reveals a surprisingly rich backstory for the fleet of sweaters used on the show. They were initially sewn by Rogers’s mother, Nancy, before she died in 1981. For the next decade, Rogers continued to wear her contributions until it became apparent they wouldn’t endure many more tapings of the show. Replacements were sought, but art director Kathy Borland quickly discovered that the search was not unlike trying to replace Superman’s cape. A Fred Rogers sweater needed a zipper with a smooth operation so it wouldn’t snag on camera. It also needed to be vibrant.

Nothing fit the bill until Borland saw a United States Postal Service employee walking down the street in Pittsburgh, Pennsylvania—where the show taped—and took note of his cardigan. Borland phoned postal supply distributors and was able to secure a fresh inventory of sweaters (which she bought white, and then dyed) that kept Rogers looking like himself through the show’s final episode in 2001.

That wasn't Rogers's only connection to USPS. In 2018, the agency dedicated a Forever stamp in his honor, with a print run of 15 million.

For more on why Borland had to perform fabric surgery on the collars and why Rogers had to reconsider his wardrobe after meeting Koko the gorilla, head over to Smithsonian. And if you want to see one of Rogers’s original sweaters made by his mother, you can check in with the Smithsonian National Museum of American History. Rogers donated one of them to the institution in 1984.

[h/t Smithsonian]