China has the most large dams of any country in the world, with roughly 24,000, including the Three Gorges Dam, the largest power station on Earth. The United States is second with around 9,000 large dams, followed by India, Japan, Brazil, South Korea and Canada.
Introduction
Dams are among the most consequential structures humans build. They generate electricity, store drinking and irrigation water, control floods and reshape entire river systems. When engineers count "large dams," they usually mean structures at least 15 meters tall, following the definition used by the International Commission on Large Dams. By that measure, China dominates the global tally like no other nation.
China built the vast majority of its dams during the 20th and 21st centuries as part of rapid industrialization and a drive for hydropower and water security. This guide ranks the leading dam-building nations and puts China's remarkable lead in context.
Countries With the Most Large Dams
The Global Leaders
- China: Roughly 24,000 large dams, by far the most of any country and about half of the world total. China's Three Gorges Dam on the Yangtze River is the largest hydroelectric power station on Earth, with a capacity of about 22,500 megawatts.
- United States: Around 9,000 large dams, the second-highest total. The US built many of its major dams in the 20th century, including the iconic Hoover Dam on the Colorado River and the Grand Coulee Dam in Washington State.
- India: More than 4,000 large dams, reflecting massive investment in irrigation and hydropower to serve its huge population. The Tehri Dam is among the tallest in the world.
Also in the Top Tier
- Japan: Around 3,000 large dams, many built in mountainous terrain for hydropower and flood control on the country's short, steep rivers.
- Brazil: More than 1,000 large dams and a global hydropower leader. The Itaipu Dam, shared with Paraguay, is one of the largest power producers in the world.
- South Korea: Around 1,000 large dams, built to manage water supply and generate power in a densely populated, mountainous country.
- Canada: Roughly 900 large dams and one of the world's biggest hydropower producers, drawing on its abundant rivers, especially in Quebec and British Columbia.
China's lead is not a matter of a few percentage points. With around 24,000 large dams, it has more than the United States, India, Japan, Brazil, South Korea and Canada combined. The scale reflects both the country's size and a sustained national policy of harnessing rivers for power, irrigation and flood management.
It is important to distinguish large dams from dams of all sizes. When smaller barriers, weirs and farm ponds are included, some countries report far higher totals: the United States, for example, counts more than 90,000 dams of every size in its national inventory. But under the internationally recognized definition of a large dam, at least 15 meters tall, China's roughly 24,000 structures place it comfortably ahead of every other nation on Earth.
Why China Leads So Decisively
- Rapid industrialization: Enormous demand for electricity drove decades of hydropower construction.
- Flood control: Rivers like the Yangtze and Yellow River have caused catastrophic floods, motivating large-scale dam building.
- Water management: Dams store and redistribute water in a country with uneven rainfall.
- Signature projects: The Three Gorges Dam alone generates as much electricity as many countries' entire power grids.
Large dams also carry costs. They can displace communities, disrupt fish migration and alter downstream ecosystems. The Three Gorges project, for example, required the resettlement of well over a million people. These trade-offs are central to modern debates about dam construction worldwide.
Quick Questions
Which country has the most dams?
China has the most large dams of any country, with roughly 24,000. That is about half of all the large dams in the world and far more than any other nation, including the United States, which ranks second with around 9,000.
What is the largest dam in the world?
The Three Gorges Dam in China is the largest power station in the world by generating capacity, at about 22,500 megawatts. It stretches more than 2 kilometers across the Yangtze River and is a central part of China's hydropower and flood-control strategy.
Does the United States have a lot of dams?
Yes. The United States has around 9,000 large dams and tens of thousands more smaller ones. Landmark structures include the Hoover Dam and Grand Coulee Dam. Even so, the US total is only a fraction of China's, which leads the world by a wide margin.