The pipeline company holds a 28 per cent interest in TC PipeLines LP, which owns U.S. natural gas pipelines and related assets.
Through the sale of the operations to the partnership, TransCanada is able to raise cash to fund its own capital spending.
"The Bison transaction advances our previously stated commitment to sell the remainder of TransCanada's U.S. natural gas pipeline assets to the partnership," TransCanada president and chief executive Russ Girling said in a statement.
"As TransCanada continues to progress our unprecedented $38 billion capital program, we intend to drop down the remainder of those assets on a more sizable, frequent basis over the coming quarters and years."
Bison is a 487-kilometre natural gas pipeline in the U.S. Rocky Mountains.