The more people learn about Fred Rogers, the more they’re falling in love with the persona and legacy of Mr. Rogers every single day.

And since he’s a wonderful man worth celebrating, let’s continue the trend and talk about one of his most distinctive features – his cardigan sweaters.

Those fuzzy, primary-colored sweaters were sewn by his mother, Nancy, before her death in 1981, but although Rogers continued wearing them on set every day, it became apparent at some point that they would have to be repaired or replaced.

Replacements, it turned out, were not easy to find. The perfect Fred Rogers sweater needed a smooth zipper and a vibrant color, and it needed to convey that warm, fuzzy quality that spilled out of the man himself.

Long story short, this was a VERY tall order!

One day, art director Kathy Borland noticed that the postal workers in Pittsburgh (where the show filmed), wore perfect cardigans for the task.

She phoned around until she found the distributor of the cardigans, then ordered a bunch of them (in white; she dyed them), and voila – Fred Rogers’ wardrobe was secured through the end of the series in 2001.

If you check out the Smithsonian exhibit on all things Fred Rogers, you can also learn about the Forever stamp dedicated in his honor, why and how Borland had to perform fabric surgery on the sweater’s collars, and why Rogers almost reconsidered his wardrobe altogether after meeting Koko the gorilla.

You can also see one of the original sweaters; Fred Rogers donated one to the museum himself in 1984!