Iranian women work on a rice field in Gilan province. Although trade sanctions are still in place, some American entrepreneurs are visiting Iranian farms and factories, exploring partnership possibilities when the long-closed commercial channels reopen. (Abedin Taherkenareh/European Pressphoto Agency)

For the first time in decades, business people from the United States are visiting Iran in significant numbers, exploring the possibility of future partnerships as Iranian and American entrepreneurs begin to envision a reopening of long-closed commercial channels.

Although sanctions blocking most types of trade between the two countries remain in place, there are no bans on travel to Iran. For U.S. citizens granted a visa to Iran, local hosts can organize programs, which have included recent visits to investment firms, Tehran’s stock exchange, factories, farms and high-tech start-ups.

The government of President Hassan Rouhani is actively promoting Iran to foreign investors but has said little about the United States specifically, although American oil giants and automakers are thought to have been in discussions with their Iranian counterparts since Rouhani took office in 2013.

Longtime partnerships in the energy and auto sectors between Iran and companies in Germany, France and Italy have dwindled in recent years because of the European Union’s own sanctions on Tehran.

Despite the drop in foreign investment from Western nations, the U.N. Conference on Trade and Development estimated that direct foreign investment in Iran is on the rise, reaching $5 billion in 2012, funded primarily by Chinese, Russian and Turkish companies.

But even that figure fell far short of the $7 billion that Iran projected for that year, and the country’s need for foreign capital is continuing to grow.

While U.S. investment is unlikely to fill that gap anytime soon, the recent visitors say the potential across multiple sectors is vast.

“There will be phenomenal opportunities for American investors. I would definitely consider investing in Iran, and I think that’s the universal answer,” said Dick Simon, chief executive of RSI, a Boston-based real estate development and investment management company, who helped organize a recent trip to Iran composed of mostly U.S. entrepreneurs, as well as several who were Canadian or British.

In the absence of diplomatic relations, such contact can serve to de-escalate tensions between the two governments — which analysts say is a strategic goal for the administrations of President Obama and Rouhani — as negotiations over Iran’s controversial nuclear program are ongoing.

“An increasing number of Americans, both inside and outside government, understand the value of whetting the appetite of business people in Iran,” said Reza Marashi, research director at the National Iranian American Council (NIAC).

According to Marashi, NIAC has been inundated this year by calls from Americans who want to travel to Iran. The organization, which favors greater contact between Americans and Iranians, is one of the few non-governmental entities in regular communication with officials in both governments.

But reopening trade will face serious challenges that may take years to resolve.

Besides sanctions and the internal guidelines of U.S.-based financial institutions, there are issues that will make investment in Iran a tough sell to U.S. companies.

“The current misperceptions and misunderstandings in America regarding Iran as a country, as a society and as a market could be the biggest obstacles” to attracting U.S. investments, said Ramin Rabii, managing director of Turquoise Partners, a Tehran-based investment firm.

Other members of Iran’s business community think that the opportunity to trade ideas and begin engaging in commerce could serve as a catalyst to improve political relations.

“The more visits like these, focused on people-to-people and business-to-business connections, the easier it will be down the road for a real and long-lasting thaw between Iran and the U.S.,” said Cyrus Razzaghi, president of Ara Enterprise, a consulting group active in business development between Iranian and foreign companies.

None of the Iranian businesses interviewed for this article have any American investors; nor do they market to them because of U.S. legal restrictions.

Beyond Iran’s energy sector, the Iranian industries seeking foreign partnerships include the rapidly growing IT and nanotechnology sectors.

Visitors from the United States say they were impressed by just how advanced the work produced by Iranian engineers and programmers was compared with the levels of other countries in the region, despite the many Internet and telecommunications restrictions imposed by authorities.

“With its remarkable geographic position and talent, Iran is seemingly poised to be a central connection between east-west and north-south if the politicians and leaders are willing to unleash it,” said Christopher M. Schroeder, a U.S.-based Internet entrepreneur and author of a recent book on start-ups in the Middle East who visited Iran in April.

“To ignore rising economies like these is to ignore where the world is going,” Schroeder said.

There are also shared opportunities in traditional industries such as agriculture, as Iran is a top fruit producer.

In a packed auditorium inside Iran’s Chamber of Commerce this month, a blueberry farmer from Winona, Minn., delivered a speech to a captivated Iranian audience.

Jim Riddle, an expert in organics who was invited to speak about U.S. regulations on organic products at an annual conference in Tehran, said his reasons for coming were to help develop Iran’s organic infrastructure, something he lectures on around the world.

“I’m not here to make business deals and find sources of ingredients, but that comes. If relations improve, I can imagine any number of products that are unique to Iran that there is and would be a demand for in the U.S.,” Riddle said.

After initial concerns that going to Iran might be illegal or potentially harmful to relations, Riddle accepted the invitation after speaking with State Department officials who told him that his trip “would be consistent with the interests of the U.S.”

In the long term and if sanctions are lifted, those interests could include the sale of a range of U.S.-produced goods as Iranians continue to hold the “made in the USA” label in high regard.

“U.S. companies could benefit from Iran’s consumption boom fueled by the demands of well-educated Iranian youth, urbanization trends and the ever-expanding consumption patterns of Iranian families,” Rabii said.