"It's Been a Long, Long Time" is a 1945 romantic ballad by Jule Styne (music) and Sammy Cahn (lyrics). Popularized by Harry James' orchestra with Kitty Kallen's vocals, it symbolizes post-WWII reunions. The song regained fame in 2019's Avengers: Endgame during Captain America and Peggy Carter's emotional reunion scene.