American Lock # 1

Tugboats stand ready to assist ocean-going
vessals maneuver through the locks

Entering American Lock #1 (MacArthur) on
the St. Mary's River from the Lake Ontario side

The lock begins to fill with the 10 million
gallons of water required to raise a ship

With the water level 21 feet above that of Lake
Ontario, the gates open onto Lake Superior
International Bridges