CHEYENNE, Wyo. - Two pipeline companies have announced plans to build an 800-mile pipeline that would bring natural gas from Wyoming to Canada and U.S. markets in the Midwest and Northeast.

Alliance Pipeline Inc. and Questar Overthrust Pipeline Company said the 42-inch Rockies Alliance Pipeline would start at Wamsutter in south-central Wyoming and traverse Wyoming, Montana and North Dakota en route to the Emerson trading hub on the Minnesota-Canada border.

The project, estimated to cost $3.5 billion, would interconnect with downstream lines to provide direct access to midwestern hubs and storage facilities, including the Chicago Hub, Michigan and Dawn storage, officials said.

The companies touted the project's ability to connect the Rocky Mountain region - the nation's fastest-growing natural gas producer - and hungry markets in the United States and central Canada.

"Rockies natural gas is an attractive alternative to Canadian gas and imported LNG," Questar President and CEO Allan Bradley said in a statement Tuesday. "Alliance and Questar Pipeline are teaming up to offer our customers seamless natural gas transportation from multiple Rockies basins to growing natural gas markets in the East. This is a project whose time has come."

Brian Jeffries, executive director of the Wyoming Pipeline Authority, welcomed the proposal as an important step in providing markets for the state's natural gas. The pipeline would carry gas from the Wamsutter hub and the Powder River Basin.

The Rocky Mountain gas industry has been ramping up pipeline construction to maximize profits on the region's plentiful supply.