How many bridges are there?
The US National Bridge Inventory holds records for over 620,000 bridges, and the count is precise because the definition is: a structure carrying a public road over an obstruction with a span of more than 20 feet, inspected at least every two years. Around 42,000 of them are rated in poor condition, and the average American bridge is over 44 years old. No global inventory exists, though China has built more large bridges in the past twenty years than the rest of the world combined.
How the figure is arrived at
A legal inspection regime, not a survey. Every state must inspect every qualifying bridge on a fixed cycle and submit standardised condition ratings to the federal government. That is why the American figure is trustworthy to four significant figures while the global one does not exist: most countries have no equivalent obligation.
How confident it is
- Low estimate
- 617,000
- High estimate
- 626,000
- Spread
- 1.0× between the bounds
Other things people built counts
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many books have ever been published? about 130 million as of 2010 — probably over 200 million now
- How many airports are there in the world? about 45,000 with runways — but only around 4,000 with scheduled airline service
- How many ATMs are there in the world? about 3 million
- How many cities are there in the world? about 10,000 with over 50,000 people; 33 megacities over 10 million
- How many buildings are there in the world? somewhere between 1.5 and 4 billion
- How many computers are there in the world? roughly 2 billion personal computers in use
Common questions
- How many bridges are there?
- more than 620,000 in the United States alone
- How is that estimated?
- A legal inspection regime, not a survey. Every state must inspect every qualifying bridge on a fixed cycle and submit standardised condition ratings to the federal government. That is why the American figure is trustworthy to four significant figures while the global one does not exist: most countries have no equivalent obligation.
Related pages
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many people are there in the world? Living things and the natural world
- How many stars are there in the universe? Space and the universe
- How many bones are in the human body? The human body
- How many grains of sand are there on Earth? Living things and the natural world
- How many ants are there in the world? Living things and the natural world
- How many trees are there in the world? Living things and the natural world
Sources
- Typical range compiled from manufacturer specifications — At One Place