According the histories I've read, marijuana wasn't illegal in the US until 1937. I don't know if this is the real history or not, but it sounds credible.
One of the factions that got in line in favor of criminalizing pot were the sisal growers. If you make the growing of hemp illegal, it's a bonanza for sisal vendors, because both sisal and hemp are used for making rope. This is hardly a legitimate basis for making law, but many laws come into being because of support from people just trying to advance their own self interest.
This could wind up a long post, because there is so many observations there. You are correct, the first federal legislation regarding pot was enacted in 1937. The following are quotes from the transcripts of testimony before the Congress. In other words, this is what wwas said to the Congress in order to compell them to enact a tax on pot:
"The leading newspapers of the United States have recognized the seriousness of this problem and many of them have advocated Federal legislation to control the traffic in marihuana. In fact, several newspapers in the city of Washington have advocated such legislation. In a recent editorial, the Washington Times stated:
The marihuana cigarette is one of the most insidious of all forms of dope, largely because of he failure of the public to understand its fatal qualities.
The Nation is almost defenseless against it, having no Federal laws to cope with it and virtually no organized campaign for combating it. The result is tragic.
School children are the prey of peddlers who infest school neighborhoods.
High-school boys and girls buy the destructive weed without knowledge of it capacity for harm, and conscienceless dealers sell it with impunity.
This is a national problem and it must have national attention.
The fatal marihuana cigarette must be recognized as a deadly drug and American children must be protected against it. ..."The purpose of H.R. 6385 is to employ the Federal taxing power not only to raise revenue from the marihuana traffic, but also to discourage the current and widespread undesirable use of marihuana by smokers and drug addicts and thus drive the traffic into channels where the plant will be put to valuable industrial, medical, and scientific uses. In accomplishing this general purpose two objectives should dictate the form of the proposed legislation: First, the development of a scheme of taxation which would raise revenue and which would also render virtually impossible the acquisition of marihuana by person who would put it to illicit uses without unduly interfering with the use of the plant for industrial , medical, and scientific purposes; and second, the development of an adequate means of publicizing dealings in marihuana in order that the traffic may be effectively taxed and controlled."
(Testimony of Clinton Hester, Assistant General Counsel for the Department of the Treasury, 1937)
As you can see, some of the things the Congress was led to believe are not true. Also, the purpose and intents of the tax act have not been followed. Although the Congress was led to believe that this tax act would not interfere with the industrial, medical, and scientific uses of this plant, it seems today that those positive uses are the only thing outlawed.
Which brings me to another point. A number of people believe that the true intents of pot prohibition was to shut down the hemp industry, basically because that's what happened. Here's the "conspiracy theory":
Andy Mellon was the secretary of the Treasury. This same Andy Mellon was the head of Mellon Bank, the main bank for DuPont Corporation. DuPont had just come out with patents on a wood pulp paper making process, and also patents on nylon, and a number of paint making processes. None of these products would be as efficient as industrial hemp and would be much more expensive. And so Andy Mellon appointed his Nephew in law, Harry Anslinger, to head up the Federal Bureau of Narcotics, to campaign for nearly ten years across the country, to enact federal legislation to control the use of "marihuana", in order to severely regulate the hemp industry and make the new petrochemical products more competitive.
A good example of what hapened is the current Chevy Volt. It's a real neat trick to run an electric car, but practically it is nowhere near as efficient and usable as an internal combustion engine.
And so the Government, who want us to switch to electric cars, have to come up with some kind of incentives to make the electric car competitive with the gas powered cars. They can raise the price of gas, They can offer incentives to purchase the electric car, or they can outlaw gas, or the internal combustion engine, and force us to switch to the electric car.
Andy Mellon wanted us to switch to DuPont's petrochemical processing products and papermaking and paint making patents. He would make a lot of money that way and make a lot of jobs for DuPont, to keep our nation going during the depression. But he had to deal with the hemp industry, which was far more efficient than petrochemical processing. Anything we can make out of hydrocarbons, we can make out of carbohydrates. Petroleum or vegetable oil, they both work about the same in industry.
1958 Wisconsin was the last crop of industrial hemp harvested in America.
If you want to learn more about the history of hemp, the "conspiracy theory" behind marihuana prohibition, and it's potential uses, there is a book to read. It's called "the Emporer Wears No Clothes" by a man named Jack Herer, who recently passed away. It's a book that will certainly inform and challenge people's world view abou tthe pot plant.