Earlier this month, Mayor Bill de Blasio signed a new law that calls for more transparency into the FDNY hiring process, which came after decades of legal battles within the fire department to level the playing field. NY1's Cheryl Wills took a closer look and filed the following report.

Throughout the New York City Fire Department's 150-year history, diversity has been one of its toughest battles. Regina Wilson knows firsthand. She is one of the 504 African-Americans who make up just 5 percent of the city's 10,500 firefighters.

During a tour of Vulcan Hall in Crown Heights, which is home to the fraternal organization of black firefighters, the newly installed president says some minorities still face stiff resistance.

"Some don't feel welcome," she said. "They still have a hard time."

A new book called "Firefight" explores the slow progress of integrating the department over the last century and a half.

"The fire department loves its traditions, and that includes everything, so change is hard for them," said Ginger Adams Otis, author of "Firefight."

Firefighters gathered to mark 75 years of slow but steady change.

Andrew Beard retired in 2002 after more than two decades on the job.

"I am just happy to see where we are today," he said.

"The more they see young people of color come on, I think more will follow," said Carl Havens, a retired firefighter.

Lynne Bernadotte was part of the first wave of 41 female firefighters in 1982.

"I would like to still see more women coming on," she said. "I'm very surprised and shocked that after so many years, that they still don't have the numbers up."

But women trailblazers are still to be found within the ranks. Brooke Guinan is the first transgender to integrate the department.

"Not only do I get to be a firefighter, but the department has been so wonderful and embracing of the fact that people are interested in my story and that it's provided a platform to get involved in activism," Guinan said.

Seventy-five years of activism was cause for celebration and reflection. African-American firefighters say they are proud of how far they've come, but they are hoping that the next 75 years will lead to a more level playing field.