"Most banknotes have traces of cocaine on them; this has been confirmed by studies done in several countries. In 1994, the U.S. 9th Circuit Court of Appeals determined that in Los Angeles, out of every four banknotes, on average more than three are tainted by cocaine or another illicit drug."
Cities and cocaine
Bills turned up positive for cocaine in these percentages in certain cities:
100 percent: Detroit, Michigan; Boston, Massachusetts; Orlando, Florida; Miami, Florida; Los Angeles, California
88 percent: Toronto, Canada
77 percent: Salt Lake City, Utah
75 percent: Brasilia, Brazil
20 percent: Tokyo, Japan; Beijing, China
0 percent: Zhuzhou, China