Question. Context: The sixteenth season of American Idol premiered on March 11, 2018, on the ABC television network. It is the show's first season to air on ABC. Ryan Seacrest continued his role as the show's host, while Katy Perry, Luke Bryan, and Lionel Richie joined as judges. Maddie Poppe from Clarksville, Iowa won the season on May 21, 2018, while her boyfriend Caleb Lee Hutchinson was runner-up. Poppe was the first female winner since Candice Glover in season twelve.

Question: when will winner of american idol 2018 be announced?
Answer. May 21 , 2018
What step-by-step reasoning justifies that answer?
Reasoning: The relevant information to answer the above question is: Maddie Poppe from Clarksville, Iowa won the season on May 21, 2018, while her boyfriend Caleb Lee Hutchinson was runner-up.