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Mellencamp is of German ancestry. He was born with spina bifida, for which he had corrective surgery as an infant. Mellencamp formed his first band, Crepe Soul, at the age of 14 and later played in the local bands Trash, Snakepit Banana Barn and the Mason Brothers. When Mellencamp was 18, he eloped with his pregnant girlfriend Priscilla Esterline.

Mellencamp participated in the Vote for Change tour in October 2004 leading up to the 2004 U.S. Presidential election. That same month he released the two-disc career hits retrospective Words & Music: John Mellencamp's Greatest Hits, which contained 35 of his radio singles (including all 22 of his Top 40 hits) along with two new tunes, "Walk Tall" and "Thank You" - both produced by Babyface but written by Mellencamp. In 2005, Mellencamp toured with Donovan and John Fogerty. The first leg of what was called the Words and Music Tour in the spring of 2005 featured Donovan playing in the middle of Mellencamp's set. Mellencamp would play a handful of songs before introducing Donovan and then duetting with him on the 1966 hit "Sunshine Superman". Mellencamp would leave the stage as Donovan played seven or eight of his songs (backed by Mellencamp's band) and then return to finish off his own set after Donovan departed. On the second leg of the tour in the summer of 2005, Fogerty co-headlined with Mellencamp at outdoor amphitheaters across the United States. Fogerty would join Mellencamp for duets on Fogerty's Creedence Clearwater Revival hit "Green River" and Mellencamp's "Rain on the Scarecrow." Mellencamp released Freedom's Road, his first album of original material in over five years, on January 23, 2007. He intended for Freedom's Road to have a 1960s rock sound while still remaining contemporary, and he feels that goal was achieved. "We wanted to make sure that it had the same feeling of some of the great songs from the '60s but also had the message of today and had the backbeat of today. I think we came up with a pretty timeless sounding album", Mellencamp told his online radio station in late 2006. "Our Country", the first single from Freedom's Road, was played as the opening song on Mellencamp's 2006 spring tour, and the band that opened for him on that tour, Little Big Town, was called on to record harmonies on the studio version of "Our Country", as well as seven other songs on Freedom's Road. Although Mellencamp had always been outspoken and adamant about not selling any of his songs to corporations to use in commercials, he changed his stance and let Chevrolet use "Our Country" in Chevy Silverado TV commercials that began airing in late September 2006. "I agonized", Mellencamp told USA Today's Edna Gundersen in 2007 over his decision to license "Our Country" to Chevrolet. "I still don't think we should have to do it, but record companies can't spend money to promote records anymore, unless you're U2 or Madonna. I'm taking heat because no one's ever done this before. People have licensed songs that have already been hits, but nobody's licensed a brand-new song to a major company, and people don't know how to react." Mellencamp sang "Our Country" to open Game 2 of the 2006 World Series, and the song was nominated for a 2008 Grammy Award in the Best Solo Rock Vocal Performance category, but lost to Bruce Springsteen's "Radio Nowhere." Freedom's Road peaked at No. 5 on the Billboard 200 album chart by selling 56,000 copies in its first week on the market.

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Mellencamp would play a handful of songs before introducing Donovan and then duetting with him on the 1966 hit "Sunshine Superman".