Skilling gets a look at an icebreaker in action on the Great Lakes

SAULT STE. MARIE, Mich. — Billions of dollars worth of commerce passes through the Great Lakes every year, and keeping those vital shipments flowing gets tricky when the lakes freeze in winter.

Cutting through all that ice is a big job, so Tom Skilling hitched a ride on the deck of the Coast Guard cutter Mackinaw as it crossed the upper Great Lakes to see how it's done. If the name sounds familiar, it’s also the Christmas tree ship that delivers free Christmas trees to Navy Pier the first week in December.

On a beautiful but bitterly cold day, the Coast Guard had three days to re-open the shipping lanes near the Soo Locks, an important shipping lane. But they were facing up to four feet of solid ice. After using the Mackinaw to break through the ice nearby, the Soo Locks officially opened at midnight on March 25, when the “American Century” earned this year’s bragging rights to be the very first vessel to pass through. And, as is tradition, a huge crowd of self-described "boat nerds" was there to greet them.

The Coast Guard says they can see ice on the upper Great Lakes until June.