Until 1914, ships traveling between New York City
and San Francisco had to sail all the way around the tip of South America. That
adds up to a distance of more than 13,000 miles (21,000 kilometers). The
opening of the Panama Canal in 1914 changed all that. The canal cuts across
Panama in Central America. It created a shortcut that saves ships nearly 8,000
miles (13,000 kilometers) and weeks of travel time!
WHAT IS A CANAL?
Canals are waterways dug across land. A canal looks
like a giant ditch. The bottom is flat and the sides are usually sloped. Some
canals are lined with concrete or stone. That helps prevent water from eroding
(wearing away) the sides. It can also keep water from seeping out of the canal
and into the ground.
TWO KINDS OF CANALS
There are two main kinds of canals. One kind
is used for carrying water from one place to another. Farmers rely on irrigation
canals to bring water to their crops. Many cities rely on canals for their
water supply.
Another kind of canal, called a navigation canal,
is used by boats. Navigation canals may connect different waterways, such as
major rivers or lakes. They may also connect inland port cities to a sea, lake,
or major river. Navigation canals allow ships to take short, direct routes,
instead of long, inconvenient ones. In some cities, such as Amsterdam and
Venice, a network of navigation canals are used like streets.
Some navigation canals are deep and wide. They are often
called ship canals because they are big enough for large, ocean-going
ships to sail through. Barge canals are much shallower. Barges are
flat-bottomed boats that sit high in the water, so barge canals are often just
a few feet deep.
A HILLY PROBLEM
For a long time, the main drawback with
navigation canals was that they could only cross flat land. Unlike roads,
navigation canals could not go uphill or downhill. The water would all run to
the lowest point, leaving the rest of the canal dry.
CANAL LOCKS
The invention of canal locks in the late 1400s
solved the hill problem. A lock is a section of a canal that can be closed off
by water gates at both ends. The water level in a lock can be raised or lowered
to match the level in a higher or lower section of the canal. In this way, a
boat can travel uphill or downhill.
To travel uphill, a boat enters the lock and
the gates are closed behind it. Then water from the upper section of the canal
gently enters the lock so the water level rises. When the water level in the
lock is the same as the upper section of the canal, the gates ahead are opened
and the boat can leave. The same process in reverse lets a boat travel
downhill.
AN OLD IDEA
People have dug canals for thousands of years.
Nearly 3,500 years ago, the ancient Egyptians built a navigation canal that
linked the Nile River with the Red Sea. Thousands of years earlier, in a region
of the Middle East called Mesopotamia, people began to dig irrigation canals. The
canals helped the Mesopotamians build productive farms and a rich civilization.
One of the world’s most impressive canals is
the Grand Canal of China. The first part of the canal was completed by the AD
600s. Construction continued for the next 600 years. The canal, which links
Beijing to Hangzhou, is still in use today. It extends for 1,200 miles (1,900
kilometers) and is the longest canal system ever built.
Building a canal is hard work. It was
especially difficult long ago, before the age of modern machines. Even in
Europe in the 1800s, canals were still dug by people using shovels. Can you
imagine the amount of work needed to dig a canal that extended hundreds of
miles?
PANAMA AND SUEZ CANALS
In many countries, canals form important inland
waterway systems. But the world’s most important canals are the Panama and Suez
canals.
The Panama Canal cuts across Central America and
links the Atlantic and Pacific Oceans. The canal is 40 miles (64 kilometers)
long and was completed in 1914. Today, the Panama Canal is one of the world’s
busiest canals.
The Suez Canal runs across northeastern Egypt
and connects the Mediterranean Sea with the Red Sea. The Suez canal is 121
miles (195 kilometers) long and first opened in 1869. It provides a shortcut
for ships traveling between European ports and ports in the Americas, Asia, and
Africa.
