Why did engineers need to use locks on the Erie Canal?

Locks were needed on the Erie Canal to overcome changes in elevation along the route. The canal stretches from the Hudson River in the east to Lake Erie in the west, and there is a significant difference in elevation between the two points. Locks are used to raise or lower boats so they can travel between different levels of the canal.

Here's a more detailed explanation of how locks work:

1. The boat enters the lock. The lock gates are opened, and the boat enters the lock chamber.

2. The lock gates are closed. Once the boat is inside the lock, the gates are closed behind it.

3. The water level in the lock is raised or lowered. If the boat is going uphill, the water level in the lock is raised by opening a valve that allows water to flow in from a higher level. If the boat is going downhill, the water level is lowered by opening a valve that allows water to flow out to a lower level.

4. The boat exits the lock. Once the water level in the lock matches the level of the canal on the other side, the gates are opened and the boat can continue on its journey.

Locks are an essential part of the Erie Canal, and they allow boats to travel between different elevations along the route. Without locks, the canal would not be able to function as a transportation route.