Marijuana by far outpaced other substances identified in positive drug tests reported to the FMCSA's Drug and Alcohol Clearinghouse the first six months of 2020, with 12,867 positives. The next highest was cocaine at 3,868, with positives for amphetamine and methamphetamine around 2,500 each.

Source: FMCSA Drug and Alcohol Clearinghouse, June 2020 Report