After centuries of percolating in the American South, what was first called hillbilly music began to reach more people through the new technologies of phonographs and radio. The Carter Family, with their ballads and old hymns, and Jimmie Rodgers, with his combination of blues and yodelling, became its first big stars.

During the Great Depression and World War II, country music thrived and reached bigger audiences. Bob Wills adapted jazz's big band sound to create Texas swing, and Grand Ole Opry singer Roy Acuff became a national star. Despite a divorce between two of its members, the Carter Family carried on, turning out songs that went on to be classics. Nashville slowly became Music City and the centre of the growing country music industry.

As country music adapted to the cultural changes of post-war society, Bill Monroe, Lester Flatt and Earl Scruggs transformed traditional string band music into something more syncopated - bluegrass. Out of the bars and juke joints came a new sound - honky-tonk - with electric guitars and songs about drinking, cheating and heartbreak. Its biggest star was Hank Williams, a singer who wrote songs of surprising emotional depth, derived from his troubled and tragically short life.

In Memphis, the confluence of blues and hillbilly music at Sun Studios gave birth to rockabilly, the precursor of rock and roll. Elvis Presley and Johnny Cash were at the forefront. In the recording studios of Music City, country music’s twang was replaced by something smoother - the Nashville sound. Patsy Cline became one of its biggest stars before her untimely death.

The mid to late 60s were a time of cultural upheaval and country, as much as other genres of music, reflected the profound changes in American society. Loretta Lynn wrote and performed songs that spoke to women everywhere, Charley Pride rose to stardom, when people responded to his voice instead of the colour of his skin, and Merle Haggard left prison to become the ‘Poet of the Common Man’. Johnny Cash’s life and career descended into the chaos of addiction, but he found salvation thanks to the intervention of June Carter and a landmark album.

As the Vietnam War intensified, America became more and more divided and country music was not immune. Kris Kristofferson, a former Rhodes scholar and army captain, reinvented himself as a writer whose lyricism set a new standard for country songs. And a hippie band from California, the Nitty Gritty Dirt Band, arrived in Nashville to create a landmark album that bridged the gap between generations. In 1969, Johnny Cash made a triumphant return to the Ryman Auditorium, a venue that had kicked him out years earlier for breaking the footlights. To celebrate, he brought an eclectic range of guests with him from folk, pop, and jazz as well as country music. Also profiled, the tormented early lives but uplifting careers of George Jones and Tammy Wynette, later known as 'Mr and Mrs Country Music'.

The 1970s and early 1980s saw country music entering a vibrant era of new voices and attitudes. Dolly Parton made the crossover to mainstream success and became the most famous woman in country music. In 1980 she achieved an entirely new level of national stardom when she joined Jane Fonda and Lily Tomlin in the hit Hollywood movie Nine to Five. While George Jones and Tammy Wynette seemed to live out their songs’ tragic lyrics, Hank Williams Jr emerged from his father’s shadow. He performed Hank Williams Sr’s music when he was just eight years old, debuted on the Opry at the age of 11 singing Lovesick Blues and recorded an album of his father’s hits at 14. But as soon as he turned 18, he dropped his mother as a manager.

Though no longer heard on country radio for much of the 1970s and early 1980s, bluegrass still had a strong core of avid fans. Marty Stuart toured with Lester Flatt and sometimes with the ‘father of bluegrass’, Bill Monroe. Back in his home state of Texas, Willie Nelson discovered a new music scene in Austin, where a mixture of hippies and rednecks seemed to get along and welcomed offbeat artists like Nelson, whose music became a hit. Ricky Skaggs had deep bluegrass credentials, but his time with Emmylou Harris’s Hot Band inspired him to experiment with a sound combining the acoustic instruments of a string band with something more electric. Willie Nelson and Waylon Jennings launched the ‘Outlaw’ movement, and Emmylou Harris bridged folk and rock with country music in a way that influenced a new generation of artists.

As country music’s popularity rocketed, the genre questioned whether it could stay true to its roots. The success of ‘New Traditionalists’ like Reba McEntire and the Judds suggested it could. Garth Brooks overcame rejection and exploded onto the scene. And after being left behind by his label, Johnny Cash returned to a studio with just his guitar and his unforgettable voice to record albums that sold millions of copies and earnt him the respect of the industry he helped to create. Meanwhile, Rosanne Cash came out of the shadow of her father to start her own music career.