Visualizing the World’s Busiest Ports

Mapped: All of the World’s Roads, by Continent

Once upon a time, it was said that all roads led to Rome. Now with at least 21 million kilometers of roads spanning the globe, every continent and country has its own web of crisscrossing connections, from major highways to rural drives.

And there’s no better way to see the scale and spread of roads than by visualizing them. Adam Symington from PythonMaps used data from the Global Roads Inventory Project (GRIP) to map all the roads in the world, creating an accurate representation of humanity’s need to connect.

Creating the Global Road Map

The GRIP database pulled information from a variety of sources including governments, research institutes, NGOs, and crowd-sourcing initiatives to create a harmonized dataset of geospatial road information for a 2018 paper, “Global patterns of current and future road infrastructure.”

Researchers categorized roads into types using a UN classification system, which have been visualized in three colors on this map:

This classification allowed for examining relationships between road infrastructure, development, wealth, and population distribution.

Which Country has the Largest Road Map?

With nearly 3 million kilometers of motorways, the U.S. has the largest road network in the world, nearly double that of China (1.7 million km) and three times that of India (1 million km).

The small Pacific island country of Palau has the smallest road network in the database measuring 18 kilometers. However, many overseas territories of countries have even smaller networks, with Norfolk Island being the smallest in the dataset at 10 km.

That said, when breaking the road networks down by type, the rankings change significantly.

China muscles out the U.S. with nearly double the amount of main roads (highways + primary roads). Meanwhile, Japan and Canada climb into the top 10 by largest main road networks, while India drops down to #8.

In the database, 1.8 million km or more than 50% of the U.S.’s large road map is made up of smaller local roads, giving unparalleled access across almost the entire country. It also has the world’s most secondary roads, while Argentina, India, and Australia lead the rankings with the most tertiary roads.

Regional Differences Between Types of Roads

These different types of roads have a striking effect on the regional visualizations of road maps.

In North America, the U.S. and Canada have a white-yellow hue accounting for the large number of highways, primary, and secondary roads.

In Mexico, the map takes on a distinct red tint, since tertiary and local roads account for nearly two-thirds of the country’s road network.

Something similar occurs in Europe, where old Cold War divisions play out in white, yellow, and red. France, Germany, Italy, and the U.K. glow hot in a mix of white and yellow, while former Eastern Bloc countries simmer more in red.

GRIP found that main roads (highways + primary) are usually found in North America, Europe, and China, while the rest of the world has a greater percentage of secondary (yellow) and tertiary and local (red) roads.

However, one interesting sidebar is that the four countries with the greatest percentage of main roads are all from the Middle East.

While there may be reasons for this, it’s possible it could also be a quirk in the database, depending on how data is collected or classified in the region.

What Do Road Networks Tell Us About Countries?

Analysis of the GRIP database found that “total road length in a country is strongly and positively related to its total land surface area, human population density, gross domestic product, and OECD membership.”

However, of all the correlations, population density is perhaps the most visible in snapshots of the larger world map, such as in this one of Asia.

The Indian subcontinent and Eastern China are the two most populous regions of the world, accounting for nearly 35% of the world’s population. The most populous regions within—especially in China—have more roads, representing growing cities and urban centers.

The opposite is visible in Africa and Australia, where large natural features like deserts prevent human settlement and roads vanish from the visualization as well.

Road Maps and Sustainable Development

The environmental impact of economic development is also visual on these road networks.

Road construction leads to emissions and biodiversity displacement. By matching road maps with natural environment visualizations like this forest map, we can see how much of the world’s pristine natural reserves are still untouched by humankind.

In South America for example, the Amazon rainforest accounts for a large chunk of Brazil’s lacking road coverage.

Finally, though the GRIP research attributes population and affluence as key correlations with road development, other economic factors drive road network expansion as well.

The researchers estimate that there will be 4 million kilometers of additional roads covering the Earth by 2050, even under conservative assumptions.

In the never-ending balancing act of sustainable development and economic prosperity, development of the world’s road map will have ripple effects for years to come.