The U.S. Air Force!
Originally, the song was known as the 'Army Air Corps Song.' Captain Robert MacArthur Crawford wrote the lyrics and music in 1939. In 1947, the words "U.S. Air Force" in the title and lyrics replaced the original "Army Air Corps". On September 27, 1979, General Lew Allen, Jr., Chief of Staff of the Air Force, adopted it as the official song for the service.

In 1937, Assistant Chief of the Air Corps Brig. Gen. Hap Arnold persuaded the Chief of the Air Corps, Maj. Gen. Oscar Westover, that airmen needed a song reflecting their unique identity, and proposed a song competition with a prize to the winner. However, the Air Corps had no control over its budget, and could not give a prize. Liberty magazine stepped in, offering a purse of $1,000 to the winner.

Around 757 compositions were entered, and evaluated by a volunteer committee chaired by Mildred Yount, the wife of a senior Air Corps officer, and featuring several distinguished musicians. The committee had until July 1939 to make a final choice. However, word eventually spread that the committee found no songs that satisfied them, despite the massive number of entries. Arnold, who took over command of the Air Corps inĀ 1938 after Westover was killed in a plane crash, solicited direct inquiries from contestants, including Irving Berlin, but not even Berlin's creations proved satisfactory. Just before the deadline, Crawford entered his song, which proved to be a unanimous winner.

The song did not catch favor with everyone. At a dinner in September 1939, committee chair Yount played a recording of the song for Charles Lindbergh and asked his opinion of the song. He responded politely to Yount, but years later remarked in a diary, "I think it is mediocre at best. Neither the music nor the words appealed to me." Arnold did not share Lindbergh's opinion; he sought to fund publication of band and ensemble arrangements of the song for nationwide distribution. However, the Air Corps did not have enough money to widely publish the piece, so Crawford arranged a transfer of the song's copyright to New York music publisher Carl Fischer Inc., including a perpetual performance release in favor of the U.S. Air Force.
Official Lyrics

Off we go into the wild blue yonder, Climbing high into the sun;
Here they come zooming to meet our thunder, At 'em boys, Give 'er the gun!
Down we dive, spouting our flame from under, Off with one hell of a roar!*
We live in fame or go down in flame. Nothing'll stop the U.S. Air Force!

Minds of men fashioned a crate of thunder, Sent it high into the blue;
Hands of men blasted the world asunder; How they lived God only knew! (God only knew!)
Souls of men dreaming of skies to conquer Gave us wings, ever to soar!
With scouts before and bombers galore. Nothing'll stop the U.S. Air Force!

Here's a toast to the host Of those who love the vastness of the sky,
To a friend we send a message of his brother men who fly.
We drink to those who gave their all of old,
Then down we roar to score the rainbow's pot of gold.
A toast to the host of men we boast, the U.S. Air Force!

Off we go into the wild sky yonder, Keep the wings level and true;
If you'd live to be a grey-haired wonder Keep the nose out of the blue!
Flying men, guarding the nation's border, We'll be there, followed by more!
In echelon we carry on. Nothing can stop the Air Force!
Nothing can stop the U.S. Air Force!

"The U.S. Air Force" is the official song of the United States Air Force. It is informally known as "The Air Force Song," and is often informally referred to as "Into the Wild Blue Yonder", "Off We Go Into the Wild Blue Yonder," or simply "Wild Blue Yonder."