NEW YORK – Mark O’Connor was haunted.

After playing fiddle during Nashville recording sessions, he would return home but find no escape from music. Not the tunes he recorded with Dolly Parton, Emmylou Harris or Doc Watson, just melodies that came from nowhere and stuck in his head.

After six months, he surrendered.

He grabbed his violin and started playing the themes into a recorder.

“I just kind of dumped it all out – metaphorically just getting it out of my head,” O’Connor recalled during a recent interview in his New York apartment that’s decorated with his old violins, guitars, mandolins, two Grammy and six Country Music Association awards.

The recordings marked his transition from country performer to composer of what became his “Fiddle Concerto” – his first orchestral composition. Within two decades, he wrote a symphony – the “Americana” – a monumental work that made its recording debut this week with Marin Alsop conducting the Baltimore Symphony Orchestra.

Lacking formal training, O’Connor used his intuition, inspiration and drive to compose and orchestrate the concerto. On his own, he studied scores and technical manuals by the great European composers.

“When I started this I really thought, No. 1, I wouldn’t perform it, and No. 2, it would not get performed. I was just going to write it for posterity. So I came from a lucrative session career where I made enough money to buy a very nice home and I quit my career cold turkey,” he said. “I just canceled everything. I said, ‘That’s it,’ and I walked away – to a lot of people’s dismay.”

The risk paid off. By his count, he has performed “Fiddle Concerto” more than 220 times.

O’Connor, 47, has written more than 40 works – including five other violin concertos and pieces for small ensembles – using his trademark amalgamation of country, folk, bluegrass, jazz and classical styles.

He completed his symphony in 2006.

“The reason I composed this symphony was because I got tired of composing violin concertos,” O’Connor said. “I love writing for orchestra. … Doing the symphony was a real natural evolution. A lot of confluences came together.”

Drawing on themes from O’Connor’s prized work “Appalachia Waltz,” which he recorded with cellist Yo-Yo Ma and bassist Edgar Meyer, the six-movement symphony is a vivid portrait of America’s 19th-century drive west. It’s also a reflection of the composer’s family’s saga.

“Symphonies to me, like a novel, unfold and are supposed to take you some place and tell a story,” he said.

He traces his family’s story back centuries.

His father’s great-grandfather arrived in America in the 1840s during Ireland’s potato famine. The O’Connors took the northern route west, settling in St. Paul, Minn., then North Dakota, Montana and eventually reaching Seattle.

His mother’s family arrived in 1608 and was among the first Dutch settlers in New Amsterdam. After the British took over the colony, renaming it New York, the family moved to Albany. He says his eighth great-grandmother was kidnapped by Mohawk Indians and ended up marrying the chief. They later moved down the Appalachian Trail and ended up in the South in the 1800s. His grandmother, who was born in Memphis, Tenn., in 1880, moved to Seattle during World War I.

“So the journey west, both branches of my family took it, just like so many people,” O’Connor said. “And it was this journey out of our cities, towns, into whatever it was to get more land, just to get more breathing room or to get away from something. A lot of this movement was our cultural backdrop to make the music that we have. And so that was a really big inspiration for the symphony.”

The piece begins with a brilliant brass and percussion fanfare that inevitably will be compared to Copland’s “Fanfare for the Common Man.” Titled “Wide Open Spaces,” the music depicts the spirit of the American sojourn.

The next three movements take the listener to Appalachia, the Plains and the Rockies, according to O’Connor’s program notes.

Finally, in “Splendid Horizons,” the journey reaches the Pacific. After the strings quote “Appalachia Waltz,” the brass and percussion return to the opening fanfare’s theme. A final crescendo “joyously celebrates spirit, wonder, renewed optimism and hope for a brighter future,” O’Connor writes.

For O’Connor, life in Seattle wasn’t always optimistic. O’Connor, his sister and their parents lived in a 400-square-foot government project. He remembers his father as a laborer who drank and was aloof from the family. O’Connor’s mentor was his mother, who died when he was 20. A classical music lover, she gave him a guitar when he was 3 and found a classical guitar teacher two years later.

Proudly taking a trophy off a shelf in his 57th Street apartment, O’Connor said he won the award – second prize – from the University of Washington when he was 10 in a competition with college students.

The following year, he was given a violin. His talent was his ticket out. His mother took him to the South, where he developed his fiddling skills. His father approved of the trips because young Mark would bring home money from his gigs.

“If it weren’t for my musical talent, I would have been his slave, no doubt,” O’Connor said.

Does he plan to write another symphony?

“If it does mean something and it resonates to people, then I’ll do another one,” he said. “I loved doing it.”