June 1971: Nixon officially declares a "war on drugs," identifying drug abuse as "public enemy No. 1."
July 1973: Nixon creates the Drug Enforcement Administration (DEA) to coordinate the efforts of all other agencies.
1976: Former Georgia Gov. Jimmy Carter campaigns for president on a platform that includes decriminalizing marijuana and ending federal criminal penalties for possession of up to 1 ounce of the drug.
1981: The Medellin cartel rises to power.
1984: Nancy Reagan launches her "Just Say No" anti-drug campaign.
October 1986: Reagan signs the Anti-Drug Abuse Act of 1986, which appropriates $1.7 billion to fight the drug war. The bill also creates mandatory minimum penalties for drug offenses, which are increasingly criticized for promoting significant racial disparities in the prison population because of the differences in sentencing for crack and powder cocaine. Possession of crack, which is cheaper, results in a harsher sentence; the majority of crack users are lower income.
1989: President George H.W. Bush creates the Office of National Drug Control Policy (ONDCP).
December 1989: the United States invades Panama. Gen. Manuel Noriega surrenders to the DEA on Jan. 3, 1990, in Panama and is sent to Miami the next day
November 1993: President Clinton signs the North American Free Trade Agreement (NAFTA), which increases the amount of trade and traffic across the U.S.-Mexican border. This makes it more difficult for U.S. Customs to find narcotics moving across the border.
May 1995: The U.S. Sentencing Commission releases a report that acknowledges the racial disparities for prison sentencing for cocaine versus crack. The commission suggests reducing the discrepancy, but Congress overrides its recommendation for the first time in history.
Sources: Based on reporting from PBS' Frontline series and NPR staff.