On Wednesday evening (Nov. 18), Alison Krauss, Rosanne Cash, Raul Malo, Edie Brickell and many more came together at the DAR Constitution Hall in Washington, D.C., to honor Willie Nelson, the 2015 recipient of the Library of Congress’s Gershwin Prize for Popular Song.

The tribute concert was part of a two-day celebration honoring Nelson, the first country artist ever to receive the Gershwin Prize. Krauss and Jamey Johnson performed "Seven Spanish Angels," Nelson's duet with Ray Charles, while Cash sang "Pancho and Lefty," one of Nelson's many collaborations with Merle Haggard, and Malo performed "Crazy," penned by Nelson and made famous by Patsy Cline.

Nelson himself also sang -- "On the Road Again" -- but one of the most special performances of the evening came when the country icon was joined onstage by his sons Lukas and Micah for "Living in the Promiseland."

"I could not have wished for a more complete source of inspiration in life, and in music, than my father,” says Lukas Nelson. “I count myself as one of the luckiest people alive to have been born to such a noble, loving and gifted human being.”

The Nelson boys also took the stage with Neil Young; they are part of the band Promise of the Real and have been working and touring with Young recently.

On Tuesday (Nov. 17), a group of U.S. lawmakers recognized Nelson during a special presentation and display at the Library of Congress' Thomas Jefferson Building.

“It is a great honor to be receiving the Gershwin award,” Nelson says “I have been a fan of Ira and George Gershwin's music since I was a little guy."

The Gershwin Prize is named after the composers and brothers and is given to recipients who “exemplify the standard of excellence associated with the Gershwins.” During his acceptance speech, Nelson noted that "in appreciation for the award — and also I wanted to make some great music — I’ve just recorded a complete Gershwin album. It’s called Summertime.”

The Tennessean reports that Summertime is set for release on Jan. 15, the same day that Nelson's Gershwin Prize tribute concert is scheduled to air on PBS at 9PM ET.

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