"As of March 2001, 16 of the 49 State police agencies with patrol duties required officers to collect the race or ethnicity of all drivers involved in a traffic stop (table 1). Thirty-seven State agencies collected the race or ethnicity of motorists when an arrest was made, and 22 agencies did so following a vehicle or occupant search. Ten State police agencies — Arizona, Arkansas, Idaho, Illinois, Minnesota, Montana, New Mexico, North Dakota, Oklahoma, and Utah — did not require their State troopers to collect race or ethnicity data."

Source

Bureau of Justice Statistics, "Traffic Stop Data Collection Policies for State Police, 2001" (Washington, DC: US Dept. of Justice, December 2001), NCJ 191158 , p. 2.
http://www.bjs.gov/content/pu…