The Union Correctional Institution, formerly referred to as Florida State Prison, and also commonly known as Raiford Prison is a Florida Department of Corrections state prison located in unincorporated Union County, Florida, near Raiford.

Since it first opened in 1913, the prison has been expanded and restructured many times. The State Prison Farm was one of the last prisons in the United States to abolish the practice of convict leasing in 1923. In 1955 the first buildings of the East Unit were established, across the Bradford County line to the south. In July 1972, the East Unit became the new Florida State Prison, and the old prison was redesignated as the Union Correctional Institution.

As of 2016, Union remains one of the largest prisons in the Florida system. It houses a maximum capacity of 2,172 adult male prisoners at a range of security levels (Maximum, Close, Medium, Minimum, and Community).

Florida's largest and oldest correctional institution was established in 1913 to house infirm inmates who could not be leased to private businesses. The initial population of the prison was close to 600 inmates, both male and female. Given the official name of Raiford Penitentiary, the facility was referred to almost exclusively as "State Prison Farm", as convicts' duties routinely included farming the 18,000-acre (73 km) prison property. The population at the facility remained fairly constant during these early years; the number of inmates needed for the farm would dictate the initial capacity for the prison.

In January 1919, Captain J. S. Blitch was appointed warden and attempted to bring about positive change to the facility. The inmates were rewarded for their labors in the field with theatrical productions, and weekly baseball games. However, continued reports of guards beating inmates soured the positive image that Blitch was trying to publicize. Brutal treatment of inmates in the convict lease system would lead to the abandonment of convict lease in 1923. By the early 1920s, the large State Prison Farm property consisted of approximately 4,000 acres (16 km) under cultivation, kept in large part by the prisoners. Also on the property was a shoe factory that made 10 pairs of shoes per day. Living conditions in the prison were very poor. The women especially lived in horrid conditions, housed separately from the men in overcrowded, wooden dormitories.

A 1928 report on the American penal system shows that, of the 1,101 male prisoners received, 674 (61%) were of color and 427 (39%) were white. Segregation existed in all aspects of prison life, from working areas to hospitals to bathrooms.

Following the abolition of convict lease and the subsequent increase in the inmate population, the prison structure changed. In 1927, a license tag factory was constructed, adding to the already extensive production line of the prison. The Main Housing Unit ("The Rock") was erected in 1928, a major step in the process of increasing the prison population. This building was kept in use until court order in 1985. ("The Rock" remained at the prison site unused until demolition in 1999.) By 1932, the inmate population was over 2,000, and a mess hall, auditorium and library had been added. The expanding prison also added a laundry and shirt factory around this time. Shortly after, in 1935, a maximum security building was constructed, the "Flat Top". This proved vital in the expansion of the center, as from this stage forward the prison would remain a maximum security facility. This was also the year the "West Unit" was built to house female offenders which remained in use until 1954 when the Florida Correctional Institution in Ocala was opened and all the female inmates were transferred from Raiford to the new facility (the West Unit remained in use as a medical facility until 1968). In 1955, the "East Unit", a new maximum security facility was completed.

The East Unit became a separate institution in July 1972, renamed Florida State Prison. The original prison site became known as Union Correctional Institution. In 1983, a Corrections Officer was stabbed to death by two inmates. A new Death Row was constructed in 1992, coinciding with the relocation of inmates from the State Prison next door. The present-day facility still uses many of the older buildings. The prison has an eclectic range of facilities, from hearing impaired and elderly accommodation to designated confinement space. The prison also has a variety of living residences, such as cell units, house units and self-contained houses.

A 1999 report by the St. Petersburg Times took a detailed look into issues of racism and diversity in the Union Correctional Institution. The report stated that more than half of the inmates were black, and more than 75% of the guards were white. This alone was grounds for racial tension. Several officers and inmates reported a clique of racist guards, distinguishable by the cord key chains they would wear. Problems turned out to be far more significant, however, after a review of public records and court files revealed over 100 black agency employees were involved in lawsuits alleging rampant racism and discrimination in the prison system. Perhaps worst of these allegations, a black recreation manager once arrived at his desk to find across his bulletin board the letters "KKK". The report also included the story of a 1993 incident, where inmates on death row were exposed to a man wearing a KKK-style white sheet walking by their cells.

• Daniel Conahan - Murderer and possible serial killer
• Leon Davis Jr. - Serial killer and arsonist
• Wayne C. Doty - Murderer and drug robber
• Kevin D. Foster - Murderer and leader of the Lords of Chaos
• Gary Hilton - Serial killer
• Michael King - Convicted of the murder of Denise Amber Lee
• Markeith Loyd – Murderer
• Craig C. Price - Juvenile serial killer
• Glen Edward Rogers - Serial killer and rapist
• Mark Sievers - Convicted of the murder of Teresa Sievers
• Donald J. Smith - Convicted of the murder of Cherish Perrywinkle
• George Trepal - Murderer and poisoner
• Troy Victorino - Perpetrator of the Deltona massacre
• William Thomas Zeigler - Mass murderer and family annihilator
• Wade Wilson - Sentenced to 2 death sentences for the murder of two women in 2019

• Groveland Four - Four men accused of raping a woman and beating her husband
• Gary Ray Bowles - Serial killer
• Ted Bundy - Serial killer
• Robert Frederick Carr - Pedophilic serial killer and rapist
• Oba Chandler - Serial killer
• John Brennan Crutchley - Rapist, murderer, and suspected serial killer
• Franklin Delano Floyd - Kidnapper, murderer, sex offender, and possible serial killer
• Clarence Earl Gideon - Wrongfully convicted burglar
• Edward Dean Kennedy - Escapee and serial killer
• Bobby Joe Long - Serial killer and rapist
• Renaldo McGirth - Convicted of the murder of Diana Miller
• Donn Pearce - AWOL-er and counterfeiter
• Danny Rolling - Serial killer
• Randy Schoenwetter - Double murderer
• Nelson Serrano - Mass murderer
• Eddie Lee Sexton - Satanist and incestuous rapist and murderer
• Joseph P. Smith - Convicted of killing Carlie Brucia (subject of Carlie's Law)
• Dan White - Actor convicted of robbery
• James Winkles - Murderer, kidnapper and alleged serial killer
• Giuseppe Zangara - Attempted assassin of U.S. president Franklin D. Roosevelt and assassin of Chicago mayor Anton Cermak

• Blondell Wayne Tatum - Carl Hiaasen character

• McDonough, Gary W., ed. (1993). "Appendix A: A Day in Florida's State Prison". The Florida Negro. A Federal Writers' Project Legacy. University Press of Mississippi. pp. 137–143. ISBN 0878055886.

• Union Correctional Institution - Florida Department of Corrections

30°04′01″N 82°11′34″W / 30.06694°N 82.19278°W / 30.06694; -82.19278