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Hemp history

Iowa grew hemp before, and it can again

Hemp is the same plant species as marijuana, Cannabis sativa, but with very little THC. Farmers grow it for its stalks and seeds, which become rope, cloth, paper, food, and building materials. Iowa farmers have grown it before, including for the country in World War II.

Where our story starts

Our Founder, Gina Lyn Cox, first learned this history from Jack Herer’s book The Emperor Wears No Clothes. Its photographs include a wartime hemp harvest near Mason City, Iowa. That book is where the idea for the Iowa Cannabis Action Network began.

A short timeline

  • 1775: Hemp is first planted in the United States, near Danville, Kentucky. It becomes a source of sailcloth, rope, and cording. (Source: Iowa Legislative Services Agency, 2019)
  • By 1910: Iowa is one of the states growing hemp, alongside Arkansas, California, Indiana, Michigan, Minnesota, Nebraska, Pennsylvania, and Wisconsin. (Source: Iowa Legislative Services Agency, 2019)
  • 1937: The federal Marihuana Tax Act taxes and restricts hemp and marijuana alike, treating them as one plant. The same year, Iowa passes its Uniform Narcotic Drug Act, which also covers cannabis. (Source: Iowa Legislative Services Agency, 2019)
  • 1942: World War II cuts off fiber imports from the Philippines. The U.S. Department of Agriculture and the Army ask farmers to grow hemp for rope and fiber in the Hemp for Victory program. Growers were issued federal tax stamps. (Source: Iowa Legislative Services Agency, 2019)
  • 1942–1945: The federal government builds 42 hemp processing mills in Iowa, Illinois, Minnesota, and Wisconsin. More than 400,000 acres of hemp are grown nationwide. In 1943, Iowa passes a law letting federally licensed growers raise hemp for fiber. (Source: Iowa Legislative Services Agency, 2019)
  • 1945: With the war winding down, most of Iowa’s wartime hemp plants close. One local history reports that seven of Iowa’s 11 hemp plants were set to close. (Source: Humboldt Independent, via IAGenWeb)
  • 1970: The federal Controlled Substances Act puts all cannabis, hemp included, in Schedule I. Commercial hemp farming ends. (Source: Iowa Legislative Services Agency, 2019)
  • 2014: The federal Farm Bill allows hemp research pilot programs run by state agriculture departments and universities. Iowa did not start one. (Source: Iowa State University CALT)
  • 2018: The federal Farm Bill removes hemp, cannabis with no more than 0.3% delta-9 THC, from the Controlled Substances Act and lets states run hemp programs. (Source: Iowa Legislative Services Agency, 2019)
  • 2019: Governor Reynolds signs the Iowa Hemp Act (Senate File 599) on May 13, 2019. Iowa farmers can grow hemp again under a state license, up to 40 acres each. (Source: Iowa State University CALT, 2019 Iowa Acts, ch. 130)
  • 2025–2026: Congress changes the federal definition of hemp to count total THC, not just delta-9 THC. The change takes effect in November 2026. (Source: Congressional Research Service)

Volunteer: Hemp Fiber program

Our Hemp Fiber program helps Iowans learn what hemp can do and supports the farmers and businesses bringing it back. Volunteers:

  • Learn and teach how hemp becomes cloth, rope, paper, and building materials
  • Connect with licensed Iowa hemp growers and processors, and share their stories
  • Collect Iowa hemp history: family stories and photos from the World War II hemp years, shared with permission
  • Speak up for fair rules for fiber farmers with our Legislative team

This is an education and advocacy program. We don’t grow, process, sell, or give away hemp or cannabis products.

Why it matters today

  • Iowa farmers once supplied hemp fiber when the country needed it. Fair, clear rules can help them do it again.
  • The same spirit lives in Iowa Victory Gardens. In wartime, Iowans grew what the country and their neighbors needed. Our gardeners grow food for local pantries today.
  • Hemp can help clean land and water. Researchers are studying hemp for pulling heavy metals and other pollutants out of soil (2022 research review). Hemp grown this way can’t be used for food or other products. See our clean water plan.
  • Stop paying to pull up ditch weed. Wild hemp along Iowa roads is the descendant of crops like these. See our priority.
  • We advocate for lawful hemp farmers. We do not grow, sell, or distribute hemp or cannabis products.

This page is for education only and is not legal advice. Hemp farming in Iowa requires a license from the Iowa Department of Agriculture and Land Stewardship. Found an error? Email hello@iowacannabisaction.org.

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