Final answer:
From 1990 to 2001, marijuana was the most widely used illegal drug among high school seniors, despite strict drug laws targeting other substances like crack cocaine.
Step-by-step explanation:
The most widely used illegal drug among high school seniors from 1990 to 2001 was marijuana. Despite the increasing number of drug-related deaths linked to substances like heroin and cocaine, marijuana remained the most frequently violated drug law. The imposition of harsher drug laws, inspired by the prevalence of crack cocaine during the 1980s, led to severe penalties, particularly for lower income, Black, and Hispanic populations.
Crack cocaine, although offering higher profitability for dealers, became synonymous with severe addiction and socio-economic destruction. The substance specifically targeted by legislative action was crack cocaine, with the Anti-Drug Abuse Act of 1986 creating a clear disparity in sentencing between crack and powder cocaine offenses, reflecting the biases and inequalities perpetuated within the war on drugs. Nevertheless, marijuana's widespread consumption overshadowed other illicit substances, with enforcement leading to a high number of arrests for marijuana-related offenses.