STILLWATER, Minn. (AP) — A groundbreaking ceremony was held Tuesday for the new St. Croix River bridge — kicking off construction of the project that connects Minnesota and Wisconsin's economic and transit interests.

The $629 million span is scheduled to open in 2016, and will replace the old Stillwater Lift Bridge — which will become part of a hiking and biking trail. The new four-lane span will link the two states along Highway 36.

U.S. Sen. Amy Klobuchar said many people believed the project would never happen. Now, she said, she hopes the new bridge will become a symbol of unity, rather than divisiveness. The Minnesota Democrat's support for the bridge had put her at odds with political allies and environmentalists.

"After years of study, we are confident that this design will be the best fit for the environment and the best fit for the community," Minnesota Department of Transportation Commissioner Charlie Zelle said in a statement.

He said the bridge is an "extradosed" design, which combines the girder bridge and cable-stay bridge models, and is the result of a collaborative effort to eliminate environmental impacts of the project. Zelle added that the design has a longer bridge span, which reduces the number of piers in the water, and a lower tower height, keeping the silhouette below the bluff line.

MnDOT Project Director Jon Chiglo said the new crossing also will improve safety and ease traffic congestion in the St. Croix Valley.

The bridge will connect Oak Park Heights, Minn., and St. Joseph, Wis. Wisconsin Gov. Scott Walker said it will improve commerce in the area and create jobs.

"Creating a safer, more reliable method of transportation between our neighboring states encourages interstate travel and opens the door for new economic opportunities," he said in a statement. "At a time when jobs are of the utmost importance, I am excited to see this project moving forward, and I am confident it will have a positive impact on our local workforce."