THE POE LOCK, part of the Soo Locks.

SAULT STE. MARIE — The Soo Locks closed this week for annual season maintenance as most of the shipping season pauses on the Great Lakes.

Each year, the locks in Sault Ste. Marie close in mid-January for maintenance. The Poe Lock will reopen March 25 and the MacArthur Lock will reopen April 24.

More than 4,500 vessels, carrying up to 80 million tons of cargo, maneuver through the locks annually, said Carrie Fox, public affairs specialist of the U.S. Army Corps of Engineers.

Iron ore, coal, wheat and limestone are among the most frequently carried commodities. Opened in 1969, the Poe Lock is 1,200 feet long. The MacArthur Lock was opened in 1943 and is 800 feet long.