The inmates at North Carolina’s Hyde Correctional Institution hung three banners from the prison fence last week as supporters gathered outside. One sign asked for better food; another requested parole; the third said, “In solidarity.”

The protest came in support of a nationwide prisoner strike to call attention to the low inmate wages, decrepit facilities and harsh sentences that organizers say plague prison populations across the country. Though it is unclear how widespread such demonstrations have been, activists said they had shown a new ability to reach inmates across state lines at a time when prison unrest and in-custody deaths are frequently in the news.

“Prisoners aren’t oblivious to their reality,” said Paul Wright, the executive director of the Human Rights Defense Center and a longtime critic of prison conditions. “They see people dying around them. They see the financial exploitation. They see the injustice.”

Inmate protests have been happening for generations, but it is only in the last few years that organizers have had success coordinating from penitentiary to penitentiary and state to state. In 2010, Georgia inmates used contraband cellphones to coordinate protests across at least six prisons. And in 2016, prisoners in several states stopped reporting for work to protest their wages.