locks and dams
Waterway elevation changers
Locks and dams are paired structures that make rivers navigable for boats.
A dam controls water levels, while a lock—a chamber with gates at each end—allows vessels to move between different water elevations.
The lock fills or drains to match the level ahead, lifting or lowering boats like a water elevator: The barge passed through three locks and dams on the Mississippi.
- canalsConstructed water passages
- inland waterwaysNavigable rivers and canals
- Mississippi RiverLongest North American watercourse
- river trafficBoats traveling on waterways
- spillwaysDam overflow passages
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