"The Happiest Girl in the Whole USA" is a country and pop music song written, composed, and recorded by Donna Fargo. It is written in the voice of a newlywed girl, sung to her new husband. It has since become her signature song.

Fargo told Tom Roland in The Billboard Book of Number One Country Hits that she wrote the song with a different title originally. "It really started out to be 'Happiest Girl in the World,' but the rhyme scheme got to be too unnatural, so I changed it to 'U.S.A.' It kind of wrote itself after that."

A rumor later circulated that the line "skip-a-dee-doo-dah" was originally written as "zip-a-dee-doo-dah," and that the Walt Disney Company subsequently sued Fargo as soon as they became aware of the song and its line, demanding that the original line be changed. Fargo has since put the rumor to rest, stating that "skip-a-dee-doo-dah" was indeed the original line and that no such lawsuit ever took place.

The song, Fargo's debut single, became a number-one country hit in the spring of 1972, and subsequently became a hit on the Billboard Hot 100 pop music chart, peaking at No. 11, and Billboard Easy Listening Singles chart, where it reached No. 7. Billboard ranked it as the No. 55 song for 1972. The record earned Fargo a Grammy for Best Country Vocal Performance, Female, at the 15th Annual Grammy Awards on March 3, 1973.

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