The Heartland Expressway is a 550–mile trade corridor covering South Dakota, Nebraska, Wyoming, and Colorado.
The ribbon cutting ceremony marked the completion of South Dakota's portion of the project after 21 years.
Senator John Thune, former Rapid City Chamber Director Jim McKeon and Secretary of Transportation Darin Bergquist led the ceremony.
McKeon believed the project would be done at least 10 years sooner, but is happy with the turn out.
"You have to be flexible," he said. "You have to have perseverance and you have to continue the leadership that is necessary to get a project of this magnitude going."
The four–lane highway connects to the Great Plains International Trade Corridor—extending from Mexico to Canada.
It is the first four-lane highway to connect South Dakota to Nebraska.