Spatial Concepts
Geographers describe location, distance, and arrangement in more than one way — and the AP exam loves testing whether you can tell these closely related terms apart. This is the vocabulary you'll reach for in every unit after this one.
Absolute location is a fixed, precise position — coordinates, an address — that doesn’t depend on anything else. Relative location describes a place in terms of its relationship to somewhere else (“20 miles north of the capital”). The same pair of ideas applies to distance and direction: absolute distance is a fixed unit like miles or kilometers, while relative distance measures the time, cost, or effort of getting somewhere — a place can be physically far but relatively close if there’s a direct highway or flight.
That distinction matters because of distance decay: interaction between two places — trade, migration, communication — tends to fall off as the distance between them grows. But space-time compression describes how transportation and communication technology keep shrinking that effective distance over time. A place that took a month to reach by ship a century ago might be a few hours away by plane today — its absolute distance hasn’t changed, but its relative distance has collapsed.
Finally, three commonly confused terms describe how things are spatially distributed. Density is a count per unit of area (people per square mile). Concentration describes how closely grouped objects are, from clustered to dispersed — independent of density, since a widely dispersed population can still be dense if the area itself is small. Pattern describes the geometric arrangement — a grid, a line, a radial spread, or no clear order at all — independent of both density and concentration.