Sources to provide further illustration:

American Prohibition

Hemp is one of the oldest cultivated crops in the entire world, due to its environmental, economic, and commercial potential. In colonial times, American farmers were even required by law to grow hemp. The first U.S. flag was sewn with the fibers of the hemp stalks, and the Declaration of Independence was drafted on paper made from the woody hurds of the hemp plant. Though hemp was used widely for a variety of products and was in fact strengthening the nation, it is hard to believe that in 1937 all varieties of the Cannabis plant were banned in the United States.

After hearing how this one crop holds a number of beneficial properties, one may ask why hemp was ever even banned?

The most common answer to this question is attributed to one of the greatest policy mix ups in U.S. history. Up until the 1920’s, the term marijuana wasn’t even part of U.S. vocabulary. Due to confusion over the similar appearance between the two Cannabis varieties, hemp and marijuana, the U.S. Government banned all Cannabis plants by passing the Marihuana Tax Act of 1937. Hemp was incorrectly combined with marijuana, a stigma that remains today.

The full story though is a bit more complicated…

Around the turn of the 20th century, the hemp industry was expanding and flourishing, which would typically lead to support for further growth and development. Instead, competitors to the hemp crop, such as large companies and investors in the timber, cotton, chemical, and petroleum industries, were getting resentful because of their loss of market share. DuPont, a major business in the petrochemical industry, JD Rockefeller, with Standard Oil Company, and William Randolph Hearst, a powerful investor in the timber industry, were all beginning to feel threatened and felt that they needed to protect their investments.

Dupont, Rockefeller, and Hearst all conducted business with Andrew Mellon, Secretary of the Treasury. A highly influential man in the U.S. government, Mellon created the Bureau of Narcotics, and appointed a family member, Harry Anslinger, the new head of the program. The Bureau of Narcotics had nothing to do after Alcohol Prohibition, and with the encouragement of some of the biggest industrial players in the country, they pushed for another illegal substance to justify their existence, hemp being on the chopping block.

Anslinger began looking into rumors concerning the Cannabis plant, and began to spread false rumors. Due to his prominent voice in the government, misconceptions about citizens becoming violent while smoking Cannabis spread widely, resulting in all varieties of this staple crop, even non-psychoactive hemp, to be labeled as a narcotic. William Randolph Hearst, baron of “yellow journalism” was a leader in this crusade, as a way to protect the timber industry and helped to spread this negative misconception through a large media campaign.

The Result

In 1937, the Marihuana Tax Act was passed, and hemp prohibition took root. Anslinger's main reasoning for including all varieties of the Cannabis plant was the mere excuse that his agents would not be able to tell the difference between the beneficial hemp crop and its psychoactive cousin, termed marijuana. Furthermore, the Bureau of Narcotics needed a way to justify its existence, now that alcohol prohibition was discontinued.

Though prohibited, hemp remained highly resourceful. The national propaganda campaign against the "evil weed" was put to a brief halt during WWII. After Japan seized the Philippines, hemp imports critical for victory in World War II became scarce. The U.S. Department of Agriculture recognized the country's desperation, and launched its "Hemp for Victory" program, encouraging hemp production on over 100,000 American acres. Hemp came to the rescue, providing the essential materials needed for victory in WWII. However, immediately after victory over fascism, the crop was federally banned yet again, a ban that remains in place even with 28 states voting to legalize hemp once again.

To this day, the misconception remains, though this colonial cash crop is gaining momentum once again. It's about time, too. Our land is depleted, our air is polluted, and our bodies are filled with modified foods and synthetic chemicals. Our nation is finally breaking the misunderstanding of this crop, a crop that can bring econoimc growth an American agricultural resurgence.