How the Panama Canal Works

The Panama Canal was built because what could possibly be more annoying than shipping something from from San Francisco to New York (or Tokyo to London) by going all the way around South America. The canal would save ships almost 8,000 miles of voyage and a ton of time and costs along the way.


So the French embarked on the project in 1881 only to bail when engineering problems and high worker mortality proved too costly. The US, under the rad Teddy Roosevelt, picked things back up in 1904 and finished it by 1914. The whole project cost $921 million, which is almost $10 billion today, but if you take the portion of the GDP $921 million was at the time, it would be like the US spending $119 billion today.

And everyone knows about the Panama Canal, but most people don’t realize how it works.

When people picture the canal, they sometimes just imagine a full slot of land carved out, leaving a little bar of ocean cutting through Panama. What’s actually happening is that the canal is more like a groove, or a man made river, that runs across the surface of the land, and ships go up over the surface in order to get across. At the highest elevation, ships are 85 feet (26 meters) above sea level.

But how can a 950 foot ship go uphill?

Here’s how:

The Panama Canal system of locks allows ships to ascend and descend in steps, like a staircase, keeping them perfectly level at all times. There are three upward steps and three downward steps. When this system was built in 1914, it was one of the greatest works of engineering in history.

Here’s a map of the canal showing where the locks are, and here’s an animation that shows exactly how the locks work (with the heights exaggerated):

Panama Canal Locks-Animation


  • Noah

    Question: where does the water in the top level come from? Is it pumped from the ocean/other levels? Also locks are amazing.

    • Jake

      There’s a large lake on top called Lake Gatun.

    • Leonardo Bosi

      According to Wikipedia the water comes from a lake and gets to the locks by means of gravity.

  • V

    Interesting article, as usual.
    I’ve been wondering. When converting the costs into today’s money, in addition to looking at the inflation / percentage of GDP, it might be interesting to look at it from the resource perspective. I mean – “the project took this much of resource 1, that much of resource 2, this many joules of energy (including human work), so today it would cost this much”.

  • Robyn Summerlin

    A few years ago I watched a PBS program on the Panama Canal, a project the US took up after the French abandoned it, walking away from 10 years of construction and a losing battle to malaria and yellow fever. About the same time I came across an article explaining how revolutionary ideas often require political influence to become generally accepted, using the Panama Canal project during Teddy Roosevelt’s administration as a prime example. In this instance it was the opinion of one man who believed that the yellow fever virus was carried by mosquitoes rather than the conventional medical wisdom of the day, that it was spread by swamp gas or poor sanitation.

    Actually, the same theory was floated by an Indian physician in the 5th Century, but because it had no political connection, his opinion never got traction. In the case of Panama Canal construction, all of the elements were in place–economic justification, Roosevelt’s political career, world opinion and a limited time to complete the project.

  • Pim Smit

    Good old PBS! Robyn Summerlin.

  • The estate I lived on as a kid (in Stoke-on-Trent, UK) is where James Brindley, inventor of the canal lock, lived back in the 1700’s. His prototype lock is buried underneath the car park of the pub erected when the estate was built, aptly called the Brindley’s Lock.

    • Mark Monnin

      Luckily, there’s an episode of Curious George, “Little Fish, Littler Pond”, to explain to kids how locks work :).

      • You wouldn’t happen to be Mark Monnin of Icrontic fame would you? If so, small world!

        • Mark Monnin

          Nope, that’s not me. Born the same year, though. Also, can you explain the fame? It looks like that user was only active during Dec 2012.

  • Bob w

    The gulf side is west of the pacific side.

  • André Baptista

    What if they make a railway linking both sides of Panama? It would be far cheaper, faster to build and more or less the same eficiency (time to unload the ship one side plus time to load other ship in the other side equals to time to pass through the canal).

    Each complete trip would use 2 ships, but they could return with cargo, making all half-trips always loaded.

    I don’t know if I’m being clear.

    • Alexander Smit

      A Panama-canal transit takes about 14 hours. I highly doubt you could unload a Panamax size containership (~5000 containers), put it on a train to the other side of the country and load another Panamax size vessel again in less than 14 hours.
      Not sure about costs though, it might very well be cheaper to build the infrastructure you suggest.

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