John Moon stands on the 2000 block of Centre Avenue in Pittsburgh's Hill District. He's in front of a building that houses the Hill District Federal Credit Union, but he points to a plaque affixed to the stone façade commemorating the Freedom House ambulance service, widely acknowledged as the first paramedic program in the United States.

A half-century ago, Moon was a Freedom House paramedic, and he remains fiercely proud of it: The service, staffed overwhelmingly by Black men from the neighborhood, revolutionized emergency street medicine on the same blocks where many were underemployed, or even believed to be "unemployable."

"We were considered the least likely to succeed by society's standards," said Moon, who was 22 and a hospital orderly when he started training to join Freedom House. "But one problem I noticed is, no one told us that!"

Today, however, Moon worries that Freedom House is in danger of being forgotten – a victim not just of time, but of the deliberate erasure of its memory.

"Unfortunately, today there are probably people who live here that has never heard of Freedom House ambulance service," he said.

A new book could help.

"American Sirens" (Hachette Books), by Kevin Hazzard, tells the story of Freedom House, which operated from 1967-75, its historic accomplishments, and its unjust and untimely demise.

Moon, himself, plays a central role. He spent much of his childhood in an Atlanta orphanage before relatives living in the Hill adopted him. As an orderly at Oakland's Montefiore Hospital, he was astonished one night when two Black men entered with a patient on a stretcher, giving orders and clearly in command – a nearly unimaginable thing in those days. Moon learned they were from Freedom House, and he vowed to follow in their footsteps.