Topic 1.1 Notes – Introduction to Maps

What Maps Are

A map is a selective, symbolic picture of Earth. It is never the whole truth. A cartographer has to choose what goes in and what gets left out, so every map highlights some things and hides others.

What gets chosen:

• Area being shown, from a neighborhood to the whole world
• Time period, because a 1990 population map and a 2024 one tell different stories
• Variables shown, like language, rainfall, migration, or population
• Boundaries and units, such as countries, states, or counties
• Symbols and colors, which shape how patterns stand out
• Scale and projection, which affect detail and distortion

What to check first on any map:

• Title tells you what the map is about
• Legend/key explains symbols, colors, and shading
• Units tell you if data is total people, people per square mile, inches of rain, and so on
• Date tells you when the map is true
• Scale tells you map distance vs real distance
• Orientation tells you direction. North is common at the top, but not guaranteed.

Maps show two kinds of information:

• Qualitative means categories or types, like religion, language, or land use
• Quantitative means numbers, like population density or migration totals

Common symbols:

• Points for cities, ports, factories
• Lines for roads, rivers, borders, flows
• Areas for countries, climate zones, land cover
• Colors/shading/patterns/sizes for categories or amount

Absolute location uses latitude and longitude to pinpoint an exact spot.

Types of Maps

The two broad groups are reference maps and thematic maps. The difference is purpose.

Reference maps

Reference maps help you figure out where things are.

Common types:

• Political maps show countries, states, capitals, boundaries
• Physical maps show mountains, rivers, lakes, coastlines
• Road/transportation maps show highways, streets, rail lines, routes
• Topographic maps show elevation and relief with contour lines

Reference maps usually show many features at once. That is the clue.

Thematic maps

Thematic maps show the spatial pattern of one topic.

Common APHG types:

This comparison image pulls together four of the thematic map types you need to recognize quickly on the exam.

Thematic map types comparison

A common AP move is asking why this map type was used. Answer with the pattern it shows best.

Spatial Patterns Maps Show

Maps are useful because they reveal relationships across space.

Distance and direction

• Absolute distance is exact and measurable, like 5 miles or 8 kilometers.
• Relative distance is about time, cost, effort, or access. Two places can be close in miles but far in travel time.
• Absolute direction uses compass directions like north or southwest.
• Relative direction depends on local context, like upstream or toward downtown.

Distribution patterns

• Clustering means features bunch together
• Dispersal means features spread out

A pattern can look clustered on one map and dispersed on another if the scale changes. That shows up a lot in AP questions.

Elevation

Elevation is height above sea level. Maps show it with contour lines, spot elevations, color bands, or relief shading.

On a topographic map, the main quick reads are slope and landform shape.

Contour clues:

• Close lines = steep slope
• Wide spacing = gentle slope
• A V shape points upstream

Topographic map features and contour lines

Scale and Projection

Map scale is the relationship between map distance and real-world distance.

Types of scale:

• Ratio like 1:50,000
• Verbal like 1 inch equals 1 mile
• Graphic/bar scale

A large-scale map shows a small area with lots of detail.
A small-scale map shows a large area with less detail.

Projection means putting Earth’s curved surface onto a flat map. That always creates distortion in one or more of these:

• Shape
• Area
• Distance
• Direction

Major projections:

• Mercator preserves local shape and direction fairly well, but badly exaggerates area near the poles. Greenland looks way too big compared with Africa.
• Gall-Peters preserves area, so size comparisons are better, but shapes get stretched.
• Robinson balances distortion for a more general world map.

The comparison image below lets you see those tradeoffs quickly across several world map projections.

World map projection comparison

Projection families to recognize:

• Cylindrical
• Conic
• Planar/azimuthal

How to Read Maps on the Exam

When APHG gives you a map, read it like evidence.

• Identify the map type
• Identify the variable and units
• Describe the pattern precisely, such as clustered, dispersed, high elevation, short relative distance
• Watch for distortion from:
  • Totals vs rates/densities
  • Boundaries/reporting units
  • Class intervals on choropleths
  • Omitted information
  • Generalization from map scale
  • Projection distortion

The biggest idea here is simple. A map can show an association between two things, but the map by itself does not prove causation.