All Employees: Professional and Business Services: Investigation and Security Services in Illinois was 36.80000 Thous. of Persons in March of 2022, according to the United States Federal Reserve. Historically, All Employees: Professional and Business Services: Investigation and Security Services in Illinois reached a record high of 40.50000 in October of 2017 and a record low of 23.90000 in April of 1991. Trading Economics provides the current actual value, an historical data chart and related indicators for All Employees: Professional and Business Services: Investigation and Security Services in Illinois - last updated from the United States Federal Reserve on April of 2024.