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Cook County Sheriff’s Police History

The Beginning

The history of the Cook County Sheriff’s Police Department can be traced back to May of 1831 with the inauguration of Sheriff James Kinzie, the first Sheriff of Cook County, Illinois. Cook County itself had only been incorporated four months earlier, on January 15th, 1831.

Cook County: Growth Over the Years

When first formed, Cook County had only about 100 recorded residents in over 2,464 square miles, an area that included what was most of today’s Lake, Will, DuPage, and McHenry counties. By 1839, Cook County’s population had risen to over 4,000, and it had shrunk to its current 946 square miles of land area, its borders looking much as they do today.

By 1940, the Cook County population living within the City of Chicago had dropped to 83 percent from its high of 90 percent in 1889.

During the post-war years following World War II, new expressways (including the Eisenhower Expressway, Tri-State,  and the Edens)  made it easy to commute to new suburban homes. Post-war veterans returning home formed families, and the resulting population spurt became known as the Baby Boom. Their new suburban homes were built rapidly with the help of recently available FHA and VA home loans.

By 2010, only 52 percent of Cook County’s 5.2 million residents lived in the City of Chicago.

Patrol Increases as Suburbs Grow

The true police patrol function of the Cook County Sheriff began in the late 1920s and early 1930s with the increase of the suburban Cook County population.

In the 1930s, Highway Deputy Sheriffs were organized to patrol suburban Cook County, often on motorcycles. In 1952, the Highway Patrol deputies were reorganized into a Sheriff’s Police force, and wore a patch known as the “Tombstone” for its shape.

The patrol function continued to increase throughout the 1940s and 1950s, corresponding to post-war suburban population growth.

The Sheriff’s Police Department under Sheriff Ogilvie
On December 3rd, 1962, Richard Ogilvie was inaugurated as the 46th Sheriff of Cook County. As part of his campaign platform, he had promised a complete reorganization of the police patrol function within the Cook County Sheriff’s Office.

Sheriff Ogilvie moved forward with his plan, creating a Merit Board to test police applicants and review applicant credentials for police officer positions. The name “Cook County Sheriff’s Police Department” was adopted. The traditional Sheriff’s colors, tan and brown, were used for the new Sheriff’s Police uniform.

Sheriff Ogilvie successfully petitioned the Illinois Legislature to enact laws permanently establishing the Merit Board and a separate Sheriff’s Police Department in every county with a population over one million (now in the Illinois Counties Code, 55 ILCS 5/3-7001).

The Last 50 Years
The goal of Sheriff’s Ogilvie’s newly reorganized Sheriff’s Police was to provide high quality, professional police service to the citizens of Cook County. This continues to be the mission of the Department to this day, embraced by the Sheriffs who have since followed.

In the more than fifty years since the Sheriff’s Police was made its own division within the Cook County Sheriff’s Office, each succeeding Sheriff has continued the original mission. The Police Department has been a leader in embracing new concepts in policing, such as the full-time Crime Scene Investigator (CSI) unit; the State-certified Police Training Academy; Street Crimes and Narcotics units; and a certified Bomb Technician Team.

Today and the Future
The Sheriff’s Police is the third largest police department in the state, and within Cook County itself, is second only to the Chicago Police Department in the number of officers deployed every day.

In the years following Sheriff Ogilvie’s reorganization, the Sheriff’s Police Department has been regularly called to assist state, local, and federal law enforcement agencies. This was part of Sheriff Ogilvie’s vision to make the Sheriff’s Police a national leader, woven into the fabric of American law enforcement.


The current Sheriff, Thomas J. Dart, has orchestrated a number of initiatives since 2006 when he was sworn in to office.

With the collaboration of law enforcement agencies from around the country, Sheriff Dart leads the semi-annual National Johns Suppression Initiatives, where police target buyers shopping for sex.

In a joint effort with the Chicago Police Department, the Community Safety Team, Street Crimes Unit, and other Department components work to reduce violence and the number of illegal guns in Chicago’s most crime-prone wards.

In addition to patrolling unincorporated Cook County, the Sheriff’s Police is Ford Height’s primary and only law enforcement agency. Sheriff Dart’s vision continues to remind the community that law enforcement is invested in the community it serves.

History compiled from resources gratefully provided by Sgt. A. Douvris.