BANGOR, Maine — What began as a way to support the efforts of St. John Catholic Church in 1993 to preserve and promote its E.&G.G. Hook Pipe Organ has become a summer tradition.

The first concert of the 20th Summer Recital Series was held Thursday at the church on York Street.

This year, the series will feature organists from Maine, New Hampshire and Massachusetts. Classical works by Bach, Liszt, Schumann and Wunderlich will be performed at 7:30 p.m. Thursdays, Aug. 2 through 30.

Kevin Birch, music director at the church, for two decades promoted the organ as a unique community treasure.

He said Thursday in an email that the concert series was started “with the help of an enthusiastic cadre of volunteers and several organists who were delighted to share their talents as a way of supporting our efforts to preserve and promote Hook’s Opus 288 at St. John’s.”

The organ is the largest and one of the oldest remaining pre-Civil War organs, Birch told the Bangor Daily News in 1996. The church commissioned the Hook Brothers of Boston to build it in 1854.

Six years later, the organ, a gleaming assortment of mahogany, ebony and oak, was brought by steamboat up the Penobscot River as far as Winterport, Birch said. A horse-drawn cart transported it from there to Bangor.

Churchgoers heard it for the first time on Christmas Eve 1860, when organs were the “centerpieces” for community music-making, Birch said in 1996. The organ’s ability to imitate many different instruments, including the drum, oboe, flute, piccolo, trumpet and clarinet, made it a natural choice for all types of music, from symphonies to popular tunes to marches.

“In fact, when people wanted to hear a Sousa March, chances are they’d hear it on a pipe organ,” he said. “Sousa himself probably heard his music played on the organ.”

In addition to the regular summer concert series, the organ has been featured at July 4 concerts of patriotic music and special programs during Christmas and Easter.

Over the past 20 years, the biggest challenge Birch and the summer concert series have faced has been “getting the word out,” he said Thursday.

“We feel that the Summer Organ Concerts are a unique opportunity to hear a great American organ in a superb acoustical environment,” he said in an email. “Keeping the organ in top playing condition is more of a joy than a challenge, as it was so beautifully engineered. Efforts to keep the organ in top shape have been possible with the encouragement and great support of our pastors and parishioners.”

The greatest reward has been in the sharing, he said.

“We’ve been able to share this cultural treasure with more and more people, many who have become regular attendees and great supporters,” he said. “We’ve also welcomed distinguished organists and organ historians from throughout the United States, France,

Germany, Holland and Japan. The organists always leave with a feeling that they’ve encountered a great musical instrument — absolutely on par with the great European instruments of the 19th century.”

The hourlong recitals are free but donations are appreciated, Birch said.

20th Summer Recital Series sponsored by St. John’s Organ Society

Aug. 2 — Scott and Linda Vaillancourt of Lewiston performing works for organ and viola by Faulkes, Mulet, Part.

Aug. 9 — George Bozeman of Deerfield, N.H., performing works for organ by Bach, Durufle, Franck, Hindemith, Peeters, Schumann.

Aug. 16 — Abbey Hallberg Siegfried of Portsmouth, N.H., performing works for organ by Alain, Bach, Liszt, Paulus.

Aug. 23 — Jay Zoller of Augusta, performing works for organ by David, Schumann, Wunderlich.

Aug. 30 — Nancy Granert of Boston performing works for organ by Bach, Dupre, Schumann, Walther.