Founders John and Ruth Gelsinger and the Northport Music Theater Board of Directors announced Nov. 15 the seasonal theater on Route 1 has closed its doors for good.

NMT opened in June 2007 with a production of “The Musical of Musicals (The Musical!)” directed by Tobin Malone, who was named executive director of the General Henry Knox Museum last month. The Gelsingers said at the time the creation of the summer theater, intended to offer quality, “grown-up” lesser-known Off-Broadway shows featuring top-notch Maine performers, was the culmination of a long-held dream.

That first summer, NMT mounted an ambitious three shows in its intimate 136-seat theater. The following year, NMT mounted three summer shows and introduced its musical theater camps for children. In 2009, NMT produced three musicals, one a concert show, ran camps and put on a holiday season show in Rockland.

There were no main stage shows mounted in 2010, although the camps, which culminated in youth productions, continued and there were a couple of independent evenings, one to benefit the theater. In 2011, NMT attempted a return to form with two shows plus the camps. It mounted one musical in 2012, ran the camps and became a nonprofit entity that fall. This summer, NMT ran two camps and offered one main stage production, “The Spitfire Grill.”

In the closure announcement, the couple and NMT board stated it became more and more apparent the theater would not be able to sustain itself long term, despite attempts made to merge with other groups and to acquire financing to support the theater’s programs.

“We send heartfelt thanks at this sad time to the wonderful actors and musicians who graced the stage (and sat in the pit), the hard working directors, designers and technical support teams that created the website, the graphics and images, the sets, lighting and costumes, the enthusiastic kids that participated in the musical theater camps (and their families), the devoted volunteers, advertisers, and donators [and] our appreciative and loyal audiences. Your participation and support over the past seven years meant the world to us,” the announcement stated.