"Blue Skies" is a popular song, written by Irving Berlin in 1926.

History

The song was composed in 1926 as a last minute addition to the Rodgers and Hart musical, Betsy. Although the show only ran for 39 performances, "Blue Skies" was an instant success, with audiences on opening night demanding 24 encores of the piece from star, Belle Baker. During the final repetition, Ms. Baker forgot her lyrics, prompting Berlin to sing them from his seat in the front row.
In 1927, the music was published and Ben Selvin's recorded version was a #1 hit. That same year, it became one of the first songs to be featured in a talkie, when Al Jolson performed it in The Jazz Singer. 1946 was also a notable year for the song, with a Bing Crosby/Fred Astaire film taking its title, and two recorded versions by Count Basie and Benny Goodman reaching #8 and #9 on the pop charts, respectively. Crossing genres, Willie Nelson's recording of "Blue Skies" was a #1 country music hit in 1978. The fact that it became a No. 1 country song (especially by a Texan artist) was not entirely surprising as it clearly was a major western swing and country standard as a 1939 version by Moon Mullican and a 1962 Jim Reeves interpretation have shown.

"Blue Skies" is one of many popular songs whose lyrics use a "Bluebird of happiness" as a symbol of cheer: "Bluebirds singing a song -- Nothing but bluebirds all day long."
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http://en.wikipedia.org/wiki/Blue_Skies