Metrolinx, the provincial Crown corporation responsible for the Toronto-area commuter rail system, has bought a rail line from railway giant CN for $68 million.

Metrolinx said Tuesday it had acquired the lower portion of the Newmarket rail subdivision in central-north Toronto from Montreal-based CN, Canada's largest rail company.

The transaction gives Metrolinx full ownership of the 96-kilometre-long Barrie-Bradford GO Train corridor between downtown Toronto and Barrie, Ont., the provincial transit agency said in a release.

Go Transit, the operating division of Metrolinx, provides commuter rail and bus services in the Toronto area of southern Ontario.

"This transaction marks a milestone for the agency, giving us — for the first time — end-to-end ownership of a GO Transit rail line," said Metrolinx president and chief executive Robert Prichard, a past president and chief executive of Torstar Corp., owner of the Toronto Star newspaper and other publishing and media properties.

"This transaction with CN — an important partner of ours — will permit improvements to service between Toronto and Barrie and points in-between. Improved commuter rail and mass transit are vital to easing traffic congestion and air pollution in the [Toronto area] while improving the productivity and economic competitiveness of the region," Prichard said.

Claude Mongeau, CN's executive vice-president and incoming president and CEO, said the transaction generates value for the company.

"CN is pleased to have reached this sales agreement with Metrolinx. We have close ties with GO — most of its services in the Greater Toronto Area operate over CN's network — and we see our partnership with GO and Metrolinx continuing to drive the environmental benefits of rail in the Toronto region."

Under its sales agreement with Metrolinx, CN will continue to serve five freight customers on the lower Newmarket subdivision rail line between Highway 401 and CN's main east-west freight corridor.