The Dept of Justice has published an update on one of our longest wars, declared by President Nixon at a press conference on 17 June 1971 (more explicitly to Congress here). Only the War on Poverty (declared by LBJ on 8 January 1964) has run longer. (I have not found a date for first use of “War on Cancer”; it was not used by Nixon in 1971).
Excerpt from the Executive Summary of the National Drug Threat Assessment 2010 (red emphasis added):
Overall, the availability of illicit drugs in the United States is increasing.1 In fact, in 2009 the prevalence of four of the five major drugs–heroin, methamphetamine, marijuana, and MDMA (3,4-methylenedioxymethamphetamine)–was widespread and increasing in some areas. Conversely, cocaine shortages first identified in 2007 persisted in many markets.
… Although drug use remained relatively stable from 2007 through 2008, more than 25 million individuals 12 years of age and older reported using an illicit drug or using a controlled prescription drug (CPD) nonmedically in 2008. Each year, drug-related deaths number in the thousands, and treatment admissions and emergency department (ED) visits both exceed a million. These and other consequences of drug abuse, including lost productivity associated with abuse, the impact on the criminal justice system, and the environmental impact that results from the production of illicit drugs, are estimated at nearly $215 billion annually.