I spend my life remembering references in my field and a whole passel of allied disciplines, I hope I may be excused for not committing to memory something that I looked at once in passing. In point of fact using nothing more than the information I provided I was able to find the report I was thinkin about as wall as a whole buch of others, almost all of which contain something like:
Although statistical data is limited, there is some evidence to indicate that in certain areas minority drivers are stopped more often than whites. Harris (1997) found that for a three year period in the late 1980s, of 1,100 videotaped traffic stops on I-95 in Volusia County, Florida, more than 70% of the drivers stopped were either African-American or Hispanic even though these groups comprised only 5% of the drivers on this highway. Even though only 9 of the 1,100 stops received a ticket, 80% of about 500 searches involved African-American or Hispanic drivers and these groups were also detained on the average twice as long as whites. Harris (1997) also reported that 75% of the 732 motor vehicle searches conducted by the Maryland State Police from January 1995 through June 1996 were with African-American motorists.