At the turn of the 20th century, the world was gripped by a plague pandemic that had spread from China to port cities around the globe. So when a 41-year-old San Franciscan named Wong Chut King died of a particularly violent disease in March 1900, there were worries that the pandemic had finally reached U.S. soil.

After examining samples from King’s autopsy, the head of the city’s Marine Hospital Service confirmed those fears: the plague had come to America. And unfortunately, it never left.

King’s death marked the beginning of the United States’ first plague epidemic, which infected at least 280 people and killed at least 172 over the next eight years (the actual numbers of cases and deaths may be higher). The disease was likely introduced by rat–infested steamships arriving at California’s shores from affected areas, mostly from Asia. But instead of alerting the public, city and state officials—including the governor of California—denied there was any plague outbreak at all.

The reason for this cover-up was partly economic. There was a fear in San Francisco and the state capital of Sacramento that if news of the plague spread, it would hurt California’s economy, says Marilyn Chase, a lecturer at the UC Berkeley Graduate School of Journalism and author of The Barbary Plague: The Black Death in Victorian San Francisco.

“There was a very real threat that California’s $40 million fresh produce industry…would be lost,” she says. With that in mind, “the state actually appealed to and secured the collaboration of the surgeon general of the United States” to keep word of the disease silent.