What is the One Chicago universe on NBC and which shows are a part of it? Details explored

NBC's One Chicago franchise, created by Derek Haas, Michael Brandt, and Dick Wolf, started with Chicago Fire in 2012 and expanded with Chicago P.D., Chicago Med, and Chicago Justice.

While Wolf Entertainment's franchises such as Law & Order and FBI were primarily police procedurals set in New York, the Chicago franchise saw the production explore the worlds of doctors, firefighters, and even attorneys in the Windy City. The shows of One Chicago often have crossover connections with Wolf's other franchises, too.

While the crossovers confirm that all of Wolf's shows are set within the same universe, shows of the Chicago franchise share a direct connection because of the titular city in their names. While Chicago Justice was canceled after Season 1, the other three shows are going strong.

All the shows in the franchise have witnessed many cast exits over the years but have managed to garner good ratings and have remained immensely popular. The franchise has had 10+ crossover events featuring all three or two shows. The last crossover event was in 2019.

Read on to know more about the One Chicago franchise.

Chicago Fire, PD, Med and Justice form NBC's One Chicago universe

The One Chicago universe is made primarily of four shows that focus on the workforces in different departments in Chicago. Together, the franchise has created 689 episodes across 36 seasons, with more seasons in production.

The first show to be premiered under this umbrella was Chicago Fire, which premiered in October 2012 and follows the story of firefighters, rescue personnel, and paramedics working at Firehouse 51. The show also delves into the personal lives of its protagonists.

Following the success of Fire, the franchise developed Chicago PD, the show's first spin-off series in 2014, which follows the story of patrol officers and the Intelligence Unit of the 21st District. The central character of Sergeant Hank Voight initially debuted in Fire as an antagonist and later got his own spin-off show. There have been several crossovers between the two shows.

The franchise expanded further with Chicago Med, launched in 2015. The show follows the story of doctors and nurses working in the ER department of Gaffney Chicago Medical Center. Dr. Will Halstead of Med was introduced as the oldest brother of Chicago PD's Detective Jay Halstead, thus connecting the shows.

While many people are unaware, a fourth show called Chicago Justice was canceled after one season to create space for other shows.

What are the other shows created by Dick Wolf with frequent crossovers with the One Chicago franchise?

While the One Chicago franchise comprises Fire, PD, Med, Justice, all of Wolf's shows are part of the universe, creating the scope for epic crossovers.

His show, FBI, has turned into a fullfledged franchise, too, with multiple spin-off shows including FBI: Most Wanted and FBI: International. Both franchises — Chicago and FBI — often feature guest appearances across shows. PD's Hailey Upton appeared in FBI when she was called to New York to assist on a drug cartel case.

Wolf's other franchise, Law & Order, and its spin-offs, including Law & Order: SVU and Law & Order: Organised Crime, also often feature crossover appearances with the One Chicago universe. Apart from sharing actors such as S. Epatha Merkerson, the One Chicago franchise often crossovers with Law & Order, especially SVU.