Kentucky farmer Andy Graves recently brought his father to see the latest crop on the family farm. Moments before the 89-year-old saw the plants, he could smell them.

“When my dad walked back to see the first fields, his eyes just lit up,” Graves says. “He said the smell was so distinct. There’s no other smell like hemp.”

Hemp, a variety of the cannabis plant, once grew by the acre on the Graves’ family farm, but disappeared after authorities outlawed the crop along with its sister species of marijuana. Even though it contains nearly none of the chemical that gives marijuana its intoxicating agent, hemp has been illegal for decades in the U.S.

But Graves, who planted a small crop last year, was the first of a handful of American farmers allowed to do so under a government research program. Although his latest crop is nothing compared with the 500 acres that once stood during his grandfather’s time, it represents the beginning of a long-awaited economic revolution.

“The business that we’re talking about today is so far and above the business my father saw and knew,” Graves says.

Hemp was once a mainstay for American farmers such as those in the Graves family, but has been outlawed for generations under regulations fearing marijuana cultivation. After decades of advocacy, a boost from the growing national interest in cannabis, rapid legalization and recent bipartisan support from lawmakers, hemp could be coming back in a big, and lucrative, way.

Most people associate hemp with braided bracelets and itchy shirts worn by college students who sip organic green tea in dormitory common rooms across the country. But hemp’s biggest advocates nowadays are more interested in economics than in philosophy.

“The economics alone are enough to convince anyone,” says Eric Steenstra, executive director of the Hemp Industries Association. Despite the fact that hemp farming is illegal, the U.S. is the world’s biggest consumer of it, importing $580 million worth in 2013, with predicted double-digit percentage growth, according to Steenstra.

Hemp is legally grown in 30 countries around the world. Most of the world’s supply comes from Canada, Steenstra says. After farmers and universities started researching hemp in 1994, Canada authorized industrial production in 1998 -- and it’s been paying off.

Canadian farmers are selling hemp for CAD80 cents (64 cents) per pound, while canola sells for roughly CAD18 cents (14 cents) per pound, even though the input costs are roughly the same, according to CBC News.

The marijuana used for smoking and the hemp used for other purposes are both varieties of the same cannabis plant, but different in terms of their chemical makeup and the amount of tetrahydrocannabinol, or THC, which is responsible for inducing a high, they contain.

Canada and the European Union define hemp as containing less than 0.3 percent THC, while marijuana can contain anywhere from 10 percent to 30 percent. Generally, about 1 percent THC is considered the threshold for marijuana to “have intoxicating potential.”

When harvested, hemp can be used in a variety of ways. The seeds can be processed to create a nutrient-rich oil or a protein-rich meal, while the stalks can be turned into fiber that can be used in products such as fabric or paper.

Opponents of hemp legalization say the plants look too similar to marijuana plants used for other activities, and would give criminals an opportunity to cultivate illegal drugs in plain sight. U.S. Rep. Hal Rogers, chairman of the House Appropriations Committee, recently told Politico that the “confusion and potential commingling lends itself to an easier path for illegal marijuana growth across the country.”

However, a recent report by the Congressional Research Service outlines a few key differences. Marijuana is cultivated to stay short and bushy to facilitate as many flowers, or buds, as possible, and the plants grow close together. Hemp farmers give their plants more space and encourage them to grow tall and produce one long stalk with just a few leaves.

This approach was the most common one used for the tens of thousands of tons of hemp grown every year by American farmers once upon a time.

American farmers have been growing hemp since the late 1800s, according to the Congressional Research Service, citing the Hemp Industries Association. But state governments did have a problem with people growing the flower for psychotropic reasons and sought to restrict its recreational use.

In the 1920s, it was among a handful of regulated drugs in many states. The Uniform Narcotic Drug Act noted that “there is little or no connection between the use of hemp drugs and crime, and that consuming it in moderation “very rarely” led to violence.

The 1937 Marijuana Tax Act defined hemp, along with marijuana, as a narcotic. Although it did not criminalize its production, it did require that all farmers only grow it for medical or industrial use, and register before growing it. They also had to secure a special tax stamp.

Regardless, production still flourished. In 1943, the U.S. grew 75,000 tons of hemp fiber on a little more than 146,000 acres, and Popular Science estimated the crop size would more than double the next year.

In fact, it was a big part of the World War II effort. In 1942, a U.S. government film urged farmers to grow “hemp for victory,” after outlining how the plant had once been used for everything from the ships at sea to covered wagons of the pioneers, while typically being imported from abroad. But since sources in the Philippines and other parts of Asia were “in the hands of the Japanese,” “American Hemp must meet the needs of our Army and Navy as well as our industries.”

According to the above video, “patriotic farmers” planted 36,000 acres of seed hemp at the government’s request in 1942, with plans for more.

Production continued into the next decade, but soon petered out. By the 1950s, the federal government had imposed mandatory jail time for possession of illegal cannabis. And in 1970 came the Comprehensive Drug Abuse Prevention and Control Act, which included cannabis as a Schedule 1 substance, a category defined as “drugs with a high potential for abuse,” which also included heroin and LSD.

But that didn’t stop Americans from buying hemp products. Advocates have been lobbying to bring hemp cultivation back to the U.S. for decades, and things finally seem to be picking up steam.

“It’s becoming ever more ridiculous,” says David Bronner, CEO and president of Dr. Bronner’s Magic Soaps, a longtime advocate of hemp legalization. “Nobody brings up opium when they eat a poppy-seed bagel; this is a very similar situation.”

Photo: Reuters/Kevin Lamarque

Bronner gained notoriety in 2012 when he locked himself in a metal cage outside the White House and proceeded to process a handful of hemp plants into enough oil to spread on to a piece of bread. According to the Washington Post, police had to cut him out of the cage with a chainsaw, and he was then charged with possession of marijuana.

But things are slowly changing.

“We’ve had a lot of allies doing a lot of hard work,” Bronner says. “Plus, as marijuana itself is being rescheduled, the debate is moving forward.”

As of February, marijuana is legal for use in some form in 23 states, including two, Colorado and Washington, that allow for recreational use among adults, with Alaska and Oregon planning to join them this year. The past few years have seen marijuana brought to the forefront of policy narratives and public discussion, which has been helping raise hemp’s profile.

In 2013, a majority of Americans polled by Gallup said they were in favor of marijuana legalization for the first time ever, and their sentiments keep going strong.

“They should be separate conversations, but they are influencing each other,” Bronner says.

He’s one of many who have been advocating local production of hemp for decades now. And over the past few years they’ve gotten more and more people on board -- including a few politicians.

The 2014 Farm Bill, aka the Agricultural Act of 2014, included a provision to allow some people to begin growing industrial hemp, provided it is for “purposes of research conducted under an agricultural pilot program or other agricultural or academic research,” and complies with state law.

This means that a handful of universities and small groups of farmers, including Graves, have grown their first crops this year. With special permission from the Drug Enforcement Administration, or DEA, of course.

But that seems to be just the beginning. And the cause has been gaining traction.

U.S. Sen. Rand Paul, R-Ky., who introduced his first bill on the subject in 2007, has been leading a bipartisan movement to remove hemp from the legal definition of “marihuana.”

This January, Sen. Ron Wyden, D-Ore, introduced the Industrial Hemp Farming Act of 2015, and Rep. Thomas Massiel, R-Ky., introduced a companion bill with 50 co-sponsors on both sides of the political aisle.

“Allowing farmers throughout our nation to cultivate industrial hemp and benefit from its many uses will boost our economy and bring much-needed jobs to the agricultural industry,” Paul said in a press release last month.

And farmers such as Andy Graves certainly hope that’s true. While he knows the economic benefits of hemp, he’s also quick to point out that he takes a spoonful of the nutritious oil every day.

The family farm used to grow tobacco, but its owners ultimately decided against it more than 15 years ago.

“We realized that we were promoting the use of a product that could kill you,” he says. “Hemp, on the other hand, is nothing but good.”