ITC and MDU said terms of the agreement are still being negotiated and will not be disclosed. The project, which is still being planned, will still need other backers and financing to move forward.
ITC spokeswoman Cheryl Eberwein said MDU's participation should spur agreements with other companies.
"We see this as another important step in getting partners on board with this project," Eberwein said. "MDU is the first one we have signed and we have active negotiations with several other stakeholders."
MDU, an energy, mining and construction company with operations in 44 states and Brazil, is North Dakota's only Fortune 500 company. It also is based in a state touted as among those with the best wind energy potential in the U.S. The state is among the windiest in the nation because its flat, largely treeless terrain is at the "polar front," an area where cold air from Canada meets warm subtropical air, said Joshua Scheck, a weather service meterologist in Bismarck.
"This region has some of the best wind resources in the United States — North Dakota has been called the Saudi Arabia of wind — and this transmission project will make development of the renewable energy feasible," Terry Hildestad, MDU's president and chief executive officer, said in a statement.
MDU spokesman Rick Matteson said the exact spot where the line would begin in North Dakota has not been set. He said the project is not designed to tie in with existing wind farms in North Dakota, or to supply power to North Dakota.
"This is really geared to new development," Matteson said. "The primary objective is to connect markets to the East Coast with resources they don't have."
North Dakota would benefit from jobs during the construction phase and from tax revenue, Matteson and Eberwein said.
The line is still in the early planning stages and faces several regulatory hurdles before it's approved. Matteson said it could be years before the project is under way.
"It's a long process among state regulators, local governments and local residents," he said.
Eberwein said developers have identified 12,000 megawatts of wind-generated electricity that could be sent through the line. A megawatt is roughly enough electricity to power 1,000 homes.
Under federal law, Eberwein said, the power line also could be used to transmit electricity from other sources, some not considered so green.
"It is generation neutral," she said. "Somebody with coal or nuclear power can interconnect with that line — it's a line any generator can tap into.
"Frankly, a purely green line will have to come in a change in federal regulations," she said.