"1-4-3." It's a code that beloved children's television star Fred Rogers would say to his friends in the neighborhood — and it stands for the number of letters in the words "I love you."

Now, Pennsylvania Governor Tom Wolf has declared May 23 — the 143rd day of the year — "143 Day," a day to celebrate and honor the Pennsylvania native's kindness by following his example. According to the Fred Rogers Center, the number was a reminder of compassion, and it meant a lot to everyone's favorite neighbor.

☀️ It’s a beautiful day in the neighborhood! Today is 1-4-3 Day — Pennsylvania’s first statewide day of kindness honoring PA native, Fred Rogers. Spread the love and share your acts of kindness using the hashtag #143DayInPA. ❤️ pic.twitter.com/3TuUsz2q3R — Pennsylvania (@PennsylvaniaGov) May 23, 2019

"I've proclaimed today to be 1-4-3 Day, Pennsylvania's first statewide day of kindness," Wolf tweeted. "Join me in spreading love today and seeing just how far a little kindness can go."

Get Breaking News Delivered to Your Inbox

To help people show their neighbors a little extra kindness through simple good deeds, the state's website created a "kindness generator," which pumps out ideas such as "Donate to a local children's fund" and "Write your favorite teacher a letter."

Happy #143Day, Neighbors! Whether you say, "I love you," or "143," there are many ways to show you care about someone. pic.twitter.com/O2qzpazpNJ — Fred Rogers Productions (@FredRogersPro) May 23, 2019

The site is also tracking how many people share their kindness on social media using the hashtag #143DayinPA. By late afternoon, it had been used nearly 12,000 times.

Examples of kindness have popped up all around the state in honor of the special day.

THIS IS WHY I LOVE PITTSBURGH: Today is the 143rd day of the year, which was Mister Rogers favorite number for "I Love You." Pennsylvania has declared it a statewide day of kindness. These new signs have gone up in downtown #Pittsburgh. #143Day #143DayInPA https://t.co/ihNhE44xxk pic.twitter.com/JTRnuXOZNH — Tim Williams (@realtimwilliams) May 23, 2019

#PoffProud to announce on #143Day that these #KindKids organized a school fundraiser that made $509! The money will help a local child who has spina bifida buy a lighter wheelchair so she can participate in her favorite activities more easily. #StudentVoice @Hampton_Talbots pic.twitter.com/PmBziQTXqq — Poff Elementary (@PoffElementary) May 23, 2019