LAST MONTH, at the Library of Congress’s National Book Festival, I said to an attendee that we would have three National Book Award finalists on our “Graphic Novel Night” stage.

“Only two,” a colleague pointed out, citing Gene Luen Yang (a two-time finalist, for “American Born Chinese” and “Boxers & Saints”) and Noelle Stevenson (“Nimona”).

“Give it time,” I replied, citing my firm belief in the achievement that is “March,” Rep. John Lewis’s civil-rights graphic memoir that in August completed its trilogy.

Today, “March: Book Three” indeed was named a finalist for the National Book Award for young people’s literature. And the honor reflects not only on Rep. Lewis, but also on co-author Andrew Aydin and artist Nate Powell.

“This is amazing to me. I’m overwhelmed and deeply moved,” Lewis tells The Post’s Comic Riffs.

“It is my hope that this honor inspires many more young people, and people not so young, to read ‘March’ and to learn the transformative lessons of our ongoing struggle to create the beloved community,” adds Lewis, who becomes one of only a handful of graphic-novel authors to be named a National Book Award finalist — and the first sitting politician to do so for an illustrated work.

“When I found out, I cried,” Aydin says of the news. “I couldn’t help it. This is such an unbelievable honor.”

It was Aydin, Lewis’s digital director, who first had the idea to tell the congressman’s story of nonviolent protest in graphic-novel form.

“It’s been an incredibly long and difficult journey to get to this point,” Aydin says, “and I am deeply, deeply grateful to the judges and supporters who have gotten us here.”

The National Book Foundation also announced finalists in the categories of fiction, nonfiction and poetry; finalists receive $1,000 and a bronze medal.

The winners — who receive $10,000, a bronze medal and a statue — will be announced Nov. 16 at a New York ceremony.

“It means so much that we’ve had such a passionate response to this work, and to further increase comics’ presence in the world at large,” Powell tells The Post. “We all need this account of the young, dedicated people — who changed the fabric of our society — to understand what it takes to push our world forward.”