You might guess that it’s the Great Wall of China, which is about 1,700 miles long. But other man-made things on earth are longer, yet much less noticed, because they’re not on earth, but under it!
The longest objects on earth are actually fuel pipelines that carry oil and gas from oil fields to factories, where the fuels can be refined. The pipelines usually consist of steel tubes, a few feet across, that are buried about two feet below ground.
One oil pipeline in Canada stretches 1,775 miles, and an oil pipeline being built in the Soviet Union will be more than 2,300 miles long. A natural gas pipeline stretching from Texas to New York City measures 1,840 miles in length, and a gas pipeline in Russia is more than 2,100 miles long.
And the largest pipeline of all, a gas pipeline in Canada, is over 5,650 miles long, that’s more than three times as long as the Great Wall of China!
An oil pipeline can transport eight million gallons of oil per day!