From Robert Johnson to BB King, musicians have long flocked to Mississippi's legendary juke joints. But now, laments Richard Knight, there's no time to lose if you want to sample the authentic sound of this Southern state

In 1963, Medgar Evers, the Field Secretary in Mississippi for the National Association for the Advancement of Colored People (NAACP), was shot in the back as he walked from his car to his Jackson home. He died less than an hour later. It was one of the more cowardly acts of the Civil Rights struggle. But there was more shame to come: Evers's killer, the white supremacist Byron De La Beckwith, was twice acquitted by all-white juries. It took a further 31 years to convict him.

Medgar Evers's elderly brother Charles still lives and works in Jackson. He's the manager at WMPR 90.1 FM, a blues and gospel radio station. When I met him in his office, a desk-fan clattering like an old Dakota on take-off, he explained how he and the great bluesman BB King, from nearby Itta Bena, have staged an annual concert to remember Medgar every year since 1963.

The fact that Charles Evers, also a prominent NAACP activist, made a career in music – and chooses to commemorate his brother through music – underlines the link between the Civil Rights movement and the blues. The two go together, not least because the blues was, for years, one of the fastest routes a black kid could take out of poverty. That period and its soundtrack is, to me, as interesting as any in history. And in Jackson, the capital of the state which gave the blues to the world, the many reminders of that extraordinary time are intoxicating. You do not need to be a blues buff to get it, either: this is the Deep South, where sluggish speech, Spanish moss and slow-cooked BBQ will seduce you.

Farish Street, north of the city, is where the blues grew up in Jackson. For years the heart of the black community, Farish Street was as important to the development of the blues as was the far more celebrated, and gentrified, Beale Street in Memphis.

Through the glare of the Southern sun one can make out the words "Ross Furniture Co" on 225 Farish Street. This was the original site of HC Speir's music shop. You probably haven't heard of HC Speir, though you're likely to have heard of Sam Phillips. Phillips discovered, among others, Elvis Presley and Johnny Cash.

It's time Speir was thought of in the same breath: he discovered Sam Phillips. These were the very founders of Delta blues, a genre which would underpin the subsequent development of popular music and without whom Phillips's Sun Records would have been very different. Speir, a white businessman, began selling guitars and wind-up Victrola phonographs (early record-players) on the black side of town in the 1920s. But he became what he described as a "talent broker", passing on to record companies the best of the artists he came across in and around Jackson. So-called "race labels" such as Vocalian and Gennett learnt to trust Speir's fine ear.

The blues historian Gayle Dean Wardlow befriended Speir, who died in 1972, and says the man did not understand the full significance of his work. But without Speir, Robert Johnson might not have been heard beyond the dusty Delta street corners where he played before finding his way to Jackson back in 1935.

Farish Street is in steep decline, though its heat-faded storefronts and defunct business premises, such as Ace Records and the Crystal Palace nightclub, are so redolent of another time that it's as exciting as many more organised presentations of American history. Farish Street today would be immediately recognisable to the likes of Elmore James and Sonny Boy Williamson II – both of whom recorded for Trumpet Records on Farish Street early in their careers.

And it's not all history: the local blues singer Dorothy Moore, famous for her world-wide hit "Misty Blue" in the Seventies, started her own label, Farish Street Records, in 2002; and Malaco Records, a much bigger concern, is still going strong after 40 years.

Another survivor is Peaches, an African-American diner located next to the Alamo theatre. The Alamo once hosted celebrated talent contests, plucking the likes of Otis Spann, who would become Muddy Waters' pianist, from obscurity.

Peaches has been a Farish Street favourite since the early Sixties and little has changed either to the decor or the menu. There's a giant jukebox stacked with blues, soul and gospel records. Photos of local heroes line the walls. The menu is pure Southern soul-food: fried beans, smothered chicken, okra and huge slices of cobbler. It's good, down-home, artery-clogging stuff and if there was a branch of Peaches in Britain I would be a fat man now. Possibly dead.

While Peaches and Malaco Records have kept the spirit of the blues alive in Jackson, the more important cradles of the music – juke joints – have not fared so well.

When I first visited Jackson in 2000, I spent a memorable night at the Subway Lounge, one of the coolest and most authentic juke joints left in Mississippi. It was a one-room basement club in a residential district which was hard to find and even harder to leave. The ceiling was decorated with fairy lights, the house band were mind-blowing and alcohol was bought from a hatch in the side of the house next door. The Subway Lounge was the real thing.

So I was sad to discover in 2004 that it had closed for good, after four decades in business. The building had become unsafe and no one could find the money to put it right. But there are other juke joints still open. The Queen of Hearts is another improvised music club, hosting live bands from time to time, and every bit as rough and raucous as the Subway had been.

The Blue Front Café, some 20 miles north-west of Jackson, at Bentonia, seems almost too good to be true. This tumbledown shack oozes the blues from every broken board and loose tile. It was opened by an African-American couple in 1948 and quickly became an important venue on the Delta blues scene. Famed for strong moonshine and fried fish, it was taken over by one of the couple's sons, Jimmy "Duck" Holmes, in 1970, and it's still run by him now. "Bentonia blues" is a style in its own right and Duck is one of its last exponents. Though its name is known to blues fans around the world, few outside Mississippi have been to the Blue Front Café. That's a shame because it will not last.

I believe the blues – and the related genres jazz, soul, gospel and rock'n'roll – to be the greatest cultural contribution the United States has made. That's a big claim, but think about it. Without the blues there would not have been Jerry Lee Lewis, Johnny Cash, Elvis Presley, Otis Redding, Aretha Franklin, Ray Charles, BB King. As John Lennon said: "If there hadn't been an Elvis there would not have been The Beatles."

The blues reflected the plight of a people whose position was so vulnerable that their leader, Medgar Evers, could be killed by a man who would remain free for 31 years. One hopes it couldn't happen now. But the blues in Jackson still reflects the hardship of a people who, even now, have a way to go before Evers would have been entirely confident that his work was done.

There is still time to visit the cradle of that great creative outpouring and to see something of the culture which fostered it. But you don't have long. It's evaporating in the Mississippi heat.

Richard Knight is author of 'The Blues Highway: New Orleans to Chicago' (Trailblazer Publications)

STATE LINES: Mississippi

Population 2.8 million
Area six times size of Wales
Capital Jackson
In Union 12 December 1817
Flower Magnolia
Motto "By valor and arms"
Nickname Magnolia State

Traveller's Guide

Getting there

US Airways (0845 600 3300; flies from Gatwick to Jackson via Charlotte. Delta (0845 600 0950; flies from Heathrow via Atlanta. To reduce environmental impact, you can buy an "offset" through Abta's Reduce my Footprint initiative (020-7637 2444;

Staying there

Blues lovers can stay at the Poindexter Park Inn, 803 Deer Park, Jackson (001 601 944 1392), a beautiful B&B in a historic house full of blues memorabilia. Doubles start at $69 (£36), with breakfast.

Visiting there

Peaches Café, 327 North Farish Street, Jackson (001 601 354 9267).

Alamo Theater, 333 North Farish Street, Jackson (001 601 352 3365).

Blue Front Café, 107 E Railroad Avenue, Bentonia (001 662 755 2278).

More information; 001 601 960 1891; 001 601 359 3297