Sullivan posted the note on Twitter, and more than 400,000 people liked her tweet, and hundreds commented that the note tugged at their heartstrings.
Sullivan told KIRO-TV that she did not expect the tweet to go viral.
“I just wanted to share something cute that my dad did for me, but after it went viral, I was humbled by all the people responding saying that their parents would never do something like what my dad did. It made me very thankful to have such a loving and caring dad who constantly goes out of his way to show it,” she said. “All in all, it's been nice for my dad and I to know that we've been making people smile just with a simple tweet.”
The teen graduates from Bellarmine Preparatory School on Sunday.