In 1913; The US Government is fundamentally changed in three ways: 1) the Federal Income Tax is established, and the US monetary system is handed over to a private central bank (the federal reserve) 2) The State legislature loses its power to elect its own Senators; thereby weakening the sovereignty of state governments, and giving the federal government greater power over states.
Once the income tax was established, the government was no longer reliant on alcohol-tax revenue (or other sin taxes for that matter). It could now afford to enact prohibition laws disguised as tax laws - these statutes would include taxes that were never expected to be collected, which was okay, because congress now collected plenty of revenue by simply stealing money from the paychecks of Americans, via the income tax.
The Harrison Act imposes a tax on narcotics to those involved in their trade. The tax requires that in order to produce, sell, distribute, prescribe, or give away narcotics (opiates and coca leaves), one must register with the federal government and pay a tax. There was much debate as to the intention of this act. Some claimed it was intended simply to collect revenue and regulate commerce, while others claimed it was to prevent the casual use of opiates. Later rulings by federal courts however, interpreted the act to claim that narcotics could only be given for legitimate medical use; and what constituted 'legitimate' would be left to the interpretation of the courts. Now that one required the stamp of government approval to deal in narcotics, only physicians and pharmacists would be able to register and pay tax - therefore, those who casually sold narcotics without a registration, those who prescribed narcotics for maintenance, and those who bought narcotics from non registered sources - were federally charged with felony tax offenses. (1914)
In 1917, Congress passes a wartime act granting the President the ambiguous power of controlling all "necessaries" for national defense. Amidst an era of the anti-saloon league (ASL) and the alcohol prohibition movement, Congress would (ab)use this wartime power, using it to shut off grain and sugar supply to alcohol distilleries - what clearly followed was a defacto prohibition of alcohol during the later years of WWI.
In 1919, the 18th Amendment was passed into law, and alcohol became illegal. Important to note is that in the time following ratification of alcohol prohibition, there came to be a general sense of fear that drinkers would simply switch to narcotics like morphine and heroin. So following the successful passage of the 18th amendment, the focus was shifted back to narcotics.
Following passage of Alcohol Prohibition just months earlier, and amidst a climate of fear regarding the possible substition of alcohol with narcotics, US Supreme Court Rules that supplying narcotics to users simply to maintain them does not constitute legitimate medical practice. (1919)
Narcotics such as opium, heroin, and cocaine begin to be smuggled from abroad. (1920's)
US Treasury bans all legal heroin sales, creating a black market for heroin. (1923)
Landmark Ruling - US Supreme Court finally Rules that the federal government can in fact regulate medical practice by physicians. Doctors fall into place. (1923)
Opium Convention treaty amended at Geneva, all heroin use is prohibited. (1925)
A black market appears in NYC, while illicitly manufactured heroin analogues also appear on the street internationally. (1925)
The 1930's was a period of heavy mexican immigration. Many mexicans were migrant workers, and had brought marijuana smoking with them. This decade marked the peak of the "Reefer Madness" era (anti pot propaganda era). More Xenophobia - Mexican migrant workers served as a scapegoat for the demonization of pot.
Clandestine Heroin Analogues are banned. (1930)
As an effect of WW2, Opium routes from India & Persia are blocked, causing an opium & morphine shortage throughout Europe. Industry evolves towards the creation of synthetic analgesics which do not rely on the poppy. (1930's)
Marijuana Stamp Tax Act (1937)
WW2 begins - Another era of "Yellow Peril", this time characterized by a fear of the Japanese (1939)
Methadone introduced to US market as Dolophine (1947)
Bureau of Narcotics & Dangerous Drugs is formed
Methadone is given experimentally to addicts as a narcotic substitution drug. (1960's)
Single Convention on Narcotic Drugs. Resolutions are made that will eventually result in the Controlled Substance Act nearly a decade later. (1961)
US becomes involved in Vietnam (1965)
A counterculture emerges, largely in protest of the Vietnam war. This was the period associated with the "hippie movement". Use of marijuana, LSD, and other psychedelics was common within this counterculture. US Government responds, demonizing the counterculture and their drugs of choice.
In anticipation of his re-election campaign, President Nixon gets hard to work with an anti heroin crusade which will generate needed publicity. His administration works hard to find or manufacture easily-solved "problems" which can be represented as "victories" in his battle against crime. At times this includes inventing statistics out of thin air, and manipulating the numbers over time to show government victory, yet simultaneously, a need for more funding, time, and enforcement. (1968-1972)