Ok.
Back when alcohol prohibition was repealed in the 30's, the U.S. needed a new intoxicant to demonize. Since at the time marijuana was primarily smoked by minorities it was the one they chose.
That's when it started to be called marijuana, a foriegn name. Before that it was called hemp, and no one feared good 'ol hemp. Hemp has benefitted mankind since pre-history, providing food and oil and fiber and medicine. The draft for the U.S. Constitution was written on hemp paper, the first U.S. flag was made of hemp cloth, and the sails on ships were made of hemp (canvas=cannibus) as well as the rigging.
Also at that time DuPont was working on synthetics (nylon, etc.). A new machine had been invented that could make hemp cloth cheaper than before, but anyone could grow hemp and make cloth; if you wanted nylon you had to buy it from DuPont.
And W.R. Hearst had millions invested in timber. Hemp makes 3 times the amt of paper pulp per acre than timber does.
All these factors came about at the same time and soon Americans were told (and believed) that smoking marijuana made white women want to have sex with Negroe's, and that it's use invariably lead to heroin addiction.
Marijuana remains illegal because of economics.
Some of the industries that would be affected by legalization, total decrim. are:
-Textiles and the cotton industry.
-Pharmicuticals (marijuana is superior as a sleeping aid than Nightal and better at reducing the effects of PMS than Midol, and better and safer for hyperactivity than Ritalin and is a superior stress reducer, no more chem. tranks needed).
There wouldn't be as many cops needed, or judges or lawyers (reason enough to legalize it right there) or prisons or prison guards.
Thousands of dea agents would be laid off.
Plus the construction companies who build courthouses and prisons, drug testing labs, hell even the company that makes judge's robe's,
And the industries that sell equip for interdiction--aircraft, ships, etc.
All those would be impacted.
Several million Americans would have to find new work.
Luckily, marijuan legalization/decrim would create as many jobs as it elimanated.
Do you know that back in the early 30's Henry Ford made a car than was made primarily out of hemp, and used hemp oil for fuel?