While sitting around a campfire at the Kerrville Folk Festival in Texas four years ago, Michelle Shocked, a volunteer at the event, entertained a group of listeners with her guitar and original songs.

The next day, an Englishman named Pete Lawrence asked Shocked to record the tunes into a Sony Walkman. In less than a year, the recording was released in England as “The Texas Campfire Tapes” and shot to the number one spot within a few weeks. It remained on the charts for almost a year.

Shocked’s second album, “Short Sharp Shocked,” was picked up by Polygram Records and released in 1988. Her third album, “Captain Swing,” was recently released and she is promoting it with a world tour that brings her to the Portland City Hall Auditorium on Friday, May 4.

Born in 1962 in Dallas, Shocked ran away from home when she was 16. Shortly afterward, she returned to live with her father and was introduced to bluegrass, folk, blues, and back-porch picking sessions.

When she left home for a second time, Shocked ended up on the fringes of the San Francisco society, living with other squatters in abandoned warehouse buildings.

It was when Shocked was gathering strength as an activist for the homeless that she heard that “The Texas Campfire Tapes” had reached number 26 on the U.K. independent charts.

Since then, Shocked has, indeed, been an overnight success. She has managed to combine the heat of those back-porch sessions with a bold political awareness.

Her guitar and lead vocals continue to wind out tunes that make listeners want to stand up and dance — and think about the contradictions of the governing systems.

She said the styles of her newest album “flow like the Mississippi” and follow in the currents of Fats Domino, George Gershwin, Hoagy Carmichael, Jerry Lee Lewis, Delta blues, and African palm wine music.

“The best music, no matter what style, always has that swing,” said Shocked, and her Portland appearance promises to be filled with the swing and feeling that her fans have come to expect from her.

Michelle Shocked will appear in concert at 8 p.m. Friday, May 4 at the Portland City Hall Auditorium. The opening performance will be given by John Wesley Harding. Tickets cost $18.50 and $16.50, and may be reserved by calling 1-800-382-8080.