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examBoard: Cambridge
examType: IGCSE
lessonTitle: Flow Line and Desire Line Maps
Maps do more than just show where places are they can tell stories about how people, goods and information move from one place to another. Flow line and desire line maps are special types of maps that show movement patterns, helping geographers understand connections between different places.
Key Definitions:
Flow line maps use lines of different thicknesses to show how much of something (like people, goods, or information) moves between places. The thicker the line, the greater the volume of movement. These maps help us understand patterns of migration, trade, or traffic.
Desire line maps show the routes people want to take between places, usually drawn as straight lines connecting origins and destinations. They don't show actual routes but rather the direct connections people wish existed. They're useful for planning transport systems.
Flow line maps have several important features that help us understand movement patterns:
A good flow line map includes these key elements:
Thicker lines show greater volume or quantity of flow. For example, a thick line might represent thousands of commuters, while a thin line might show just a few hundred.
Different colours can represent different types of flow (e.g., imports vs exports) or different time periods (e.g., morning vs evening commutes).
Arrows show which way the flow is moving. Sometimes maps show flows in both directions with different colours or on opposite sides of a central line.
Transport for London uses flow line maps to show how many passengers travel between different stations on the Underground network. The thickest lines on these maps show the busiest routes, like the Central Line between Liverpool Street and Bank during rush hour. These maps help planners decide where to add extra trains or build new lines. For example, the Crossrail project (Elizabeth Line) was partly designed based on flow data showing overcrowding on east-west routes.
To create a basic flow line map, follow these steps:
For example, if you were mapping migration between countries, a line 5mm thick might represent 5 million migrants, while a line 1mm thick might represent 1 million migrants.
Desire line maps show where people want to go, not necessarily where they actually go. They're particularly useful for transport planning and urban design.
Desire line maps typically show:
Unlike flow line maps, desire lines don't show the actual routes people take just the direct connections between starting points and destinations. This helps planners see where new transport links might be needed.
Have you ever noticed worn paths across grass in parks where there are no official paths? These are physical desire lines they show where people actually want to walk, regardless of the official paths. Urban planners study these natural desire lines when designing or redesigning parks. In New York's Central Park, designers Frederick Law Olmsted and Calvert Vaux waited to see where people naturally walked before finalising some of the park's paths. This approach ensures that paths match how people actually use the space.
Flow line and desire line maps have many practical uses in geography and planning:
Transport planners use these maps to identify busy routes and plan new roads, bus routes, or train lines. By understanding where people want to go (desire lines) and how many people are currently travelling on existing routes (flow lines), they can make better decisions about transport infrastructure.
Urban planners use these maps to understand how people move around cities and where new facilities might be needed. For example, desire line maps might show that many people want to travel between a residential area and a shopping centre, suggesting a need for better transport links.
While both types of maps show movement, they have different purposes and uses:
| Feature | Flow Line Maps | Desire Line Maps |
|---|---|---|
| What they show | Actual movement of people/goods | Preferred connections between places |
| Line shape | Often follows actual routes (roads, rivers, etc.) | Usually straight lines (shortest path) |
| Main use | Analysing existing patterns | Planning new connections |
| Common examples | Trade flows, migration patterns, traffic volumes | Commuter preferences, potential transport routes |
In your iGCSE Geography exam, you might be asked to interpret or create simple flow line or desire line maps. Here are some tips:
Flow line maps are often used to show global trade patterns. A typical global trade flow map might show thick lines between China and the United States, representing the massive volume of goods traded between these economic giants. Thinner lines might connect smaller trading partners. These maps help economists and policymakers understand global economic relationships and dependencies. During the COVID-19 pandemic, such maps helped identify vulnerable supply chains when trade was disrupted.
Try creating a simple flow line map showing journey to school patterns:
This simple exercise helps you understand how flow line maps represent real-world movement patterns. You could extend this by creating a desire line map showing where students would prefer to travel if there were no obstacles (like buildings or rivers) in the way.
Flow line and desire line maps are powerful cartographic tools that help geographers understand movement patterns and connections between places. Flow line maps show actual movements with varying line thickness representing volume, while desire line maps show preferred connections with straight lines. Both are essential for transport planning, urban development and understanding human movement patterns. By mastering these cartographic skills, you'll be better equipped to analyse and represent geographical data in your iGCSE studies and beyond.
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