Maps, Population, Migration, and Settlement

Geographic Tools: Coordinates, Map Features, and Projections

To understand human societies and geography, we must first understand how to read and interpret maps. Geographers identify locations on Earth using a grid system composed of latitude and longitude lines. Latitude lines, which are also called parallels, indicate the angular distance north or south of the equator, measured in degrees. The equator itself serves as the starting baseline and is designated as 0 degrees latitude. In contrast, longitude lines, also known as meridians, indicate the angular distance east or west of the prime meridian, which is designated as 0 degrees longitude. Together, these intersecting lines allow us to identify an absolute location, which is defined by exact geographic coordinates. For everyday purposes, people also rely on relative location, which describes where a place is situated in relation to other landmarks or physical features.

Every map is a model of the real world that relies on specific standard tools to communicate information clearly. A map legend or key explains the meaning of symbols, colors, and line styles used throughout the map. A compass rose indicates cardinal directions, which are north, south, east, and west, helping the reader maintain proper orientation. To understand distance, readers look to the map scale, which represents the proportional relationship between a measured distance on a map and the actual distance on Earth. Different maps serve different purposes. Physical maps illustrate natural landscape features such as mountains, rivers, plains, and elevations. Political maps display governmental boundaries, nations, states, and major cities. Thematic maps focus on specific data sets, such as climate zones, population density, or economic activity. Topographic maps use contour lines to show variations in land elevation and terrain steepness.

Representing Earth on a flat sheet of paper always involves compromise. Because the Earth is round, all flat map projections introduce some degree of distortion in shape, area, distance, or direction. For instance, the Mercator projection preserves local shapes and shows constant compass bearings as straight lines, making it historically useful for navigation. However, the Mercator projection greatly exaggerates the size of landmasses located near the poles, causing them to appear far larger than landmasses near the equator.