A Cook County Sheriff's police car patrols the exterior of the Cook County Jail in Chicago
A Cook County Sheriff's police car patrols the exterior of the Cook County Jail in Chicago, Illinois, January 12, 2016. The Cook County Jail in Chicago -- the biggest single-site jail in the United States -- was placed on lockdown on Tuesday after staffing dropped below normal levels, said Cook County Sheriff's spokesman Ben Breit. REUTERS/Jim Young