Rory Block is asked the question time and time again. She's tired of trying to explain something she's unable to put into words: How someone who grew up in 1960s Manhattan could fall in love with early blues rooted in rural Mississippi nearly 40 years earlier.

``It's very, very hard to explain why you're drawn to things," said Block.

It was the soulful Delta blues sound of Robert Johnson that made her fall in love and never look back, she said.

``It had mystique, lure, power. It was haunting. It was beautiful," she said.

Now Block is touring with Johnson's grandson Steven, who is a singer with the Straitway Ministries Choir based in Utica, Miss.

Robert Johnson, whom Eric Clapton once called ``the most important blues musician who ever lived," recorded legendary tracks like ``Cross Road Blues ," and ``Hellbound On My Trail " during the late 1930s. Johnson lived a mysterious life, with rumors swirling about selling his soul to the devil so he could play guitar. He died at 27.

Block said she had yearned to create an album of his music since she first began playing guitar at age 14. On Tuesday, she'll be releasing a tribute album to Johnson, titled ``The Lady and Mr. Johnson." It was while she was making the tribute album that she learned of Johnson's grandson. Together they came up with the idea of the combined tour.

Block grew up in New York City. She said there was a blues roots and folk revival happening in Greenwich Village as she was growing up in the 1960s. After honing her guitar skills jamming with Reverend Gary Davis in the Bronx, Block had the chance to play for Son House , another well-known blues singer and guitarist and big influence on her.

At 15, Block left school with a few friends, her sights set on traveling to California. ``We were free spirits. We didn't know what we were doing," she said.

Along the way, Block visited the South, the region blues, roots, gospel, and country all called home and where her musical heroes found inspiration.

``Washington, D.C., on down -- you knew you were in music country," said Block. ``The whole South was a real intense musical energy."

In the mid-1960s, Block recorded and released an instructional album, ``How to Play Blues Guitar." After taking some time off to start a family, Block returned to the blues, but found that record companies were reluctant to share her passion for the music, deeming it noncommercial.

She found, however, that Rounder Records encouraged her to be true to herself.

``Artistic freedom was a gift greater than money," said Block. ``They would say, `Don't change. The charts will come to you.' " She found pleasure in songwriting, and began touring, playing her ``electric mixes" with old and contemporary blues.