Jennifer Gilbert was there with her son Jackson, 9, a seasoned fan of Star Wars and Marvel Comics. Mrs. Gilbert discovered Loot over Labor Day weekend, and Jackson has become a once-a-week regular. She has seen the benefit of him finding peers with common interests. “It has built his confidence,” she said.

Long gone are the days when comic books were seen as a bad influence on young readers.

Last year, annual sales of comics and graphic novels in the United States and Canada reached just over $1 billion, according to estimates by ICV2, an online publication that covers pop culture, and Comichron, an online resource for comics research. Part of the $80 million increase from 2017 was attributed to sales outside of comic stores, which includes chain bookstores and major online retailers, with sales of graphic novels for young readers the biggest factor.

“Graphix, the imprint from Scholastic, has really turbocharged that part of the market,” said Milton Griepp, the chief executive of ICV2. The Graphix library includes “Bone” by Jeff Smith, “Dog Man” by Dav Pilkey and the memoirs of Raina Telegemeier. Her latest, “Guts,” about tackling fourth grade and coping with anxiety, has an initial print run of one million copies.

Another significant factor, Mr. Griepp said, are libraries, which have added more graphic novels to their collections over the years. “We in the comics business owe a huge debt of thanks to the librarians who have helped make this possible.”

Paul Levitz, a former president of DC Comics, has seen the industry go through many changes. Last weekend, he happened to be dining downstairs at Frank’s when he learned about Loot and ventured to the second floor to take a look. “Loot isn’t really a comic shop — at least not yet,” Mr. Levitz wrote in an email. “It’s more of a great art experience. With arts education in public schools fiscally challenged, it’s great to have folks like this stepping up to fill the gap .”

Since stepping down from his role at DC, Mr. Levitz has been teaching graphic novel courses at colleges. He said he was impressed by some of the material on offer for Loot’s cartoonists in training, including a binder of instructions for drawing facial expressions. “I wish I had some of those tools for my college course on writing graphic novels,” he added.