Latitude: horizontal lines, measure N/S of equator (0–90°). Longitude: vertical lines, measure E/W of prime meridian (0–180°). GPS coordinates: latitude listed first.
Every flat map distorts something — know the trade-offs
Mercator (cylindrical): preserves shape and direction but inflates area at poles. Peters (equal-area): correct area but distorted shape. No projection is perfect. All are compromises.
Map Scale
Map scale 1:24,000 = 1 unit on map = 24,000 units in reality
Map Scale
How to read representative fraction scales
1 inch on a 1:24,000 map = 24,000 inches = 2,000 feet in reality. Larger scale number = smaller area, more detail (1:10,000). Smaller scale number = larger area, less detail (1:1,000,000).
Topographic Maps
Contour lines: close together = steep. V pointing uphill = valley.
Topographic Maps
How to read elevation and terrain from contour lines
Each contour line connects points of equal elevation. Close lines: steep slope. Wide lines: gentle slope. V-shapes pointing uphill = valley/stream. V-shapes pointing downhill = ridge.
GIS
GIS: Geographic Information System — layers of spatial data for analysis
GIS
Digital mapping that overlays multiple data layers for spatial analysis
GIS combines multiple data layers (terrain, population, land use, roads) for analysis. Used in urban planning, disaster response, epidemiology, environmental science. Google Maps is a simplified consumer version.
Remote Sensing
Remote sensing: satellites and aircraft collect data about Earth's surface without direct contact
Remote Sensing
Gathering geographic data from a distance
Passive sensors: detect natural energy reflected or emitted from Earth (visible light, infrared, thermal). Active sensors: emit energy and measure what bounces back (radar, LiDAR). Applications: land use mapping, crop monitoring, disaster assessment, military surveillance, climate monitoring. Google Earth uses remote sensing imagery.
Prime Meridian and Date Line
Prime meridian: 0° longitude through Greenwich, England. International Date Line: ~180° longitude.
Prime Meridian and Date Line
The two arbitrary reference lines that organize global timekeeping
Prime meridian (0°): established 1884 at Royal Observatory, Greenwich. All longitude measured east or west of it. International Date Line (~180°): where the calendar changes. Cross going west: gain a day. Cross going east: lose a day. Zigzags to avoid splitting countries (Kiribati, Fiji).
Thematic Map Types
Choropleth map: shades regions by value. Dot map: each dot = a quantity. Proportional symbol: size = value.
Thematic Map Types
Different ways to show data on maps
Choropleth: shades regions by data value (population density, income) — easy to read but misleading if regions vary in size. Dot map: each dot represents a fixed number of things — shows distribution. Proportional symbol: circle size proportional to value — shows totals. Isoline (isopleth): lines connect equal values (contours, isotherms).
Choropleth
Shaded regions by value
Dot map
Each dot = a quantity
Proportional symbol
Symbol size = value
Isoline
Lines of equal value
GPS Technology
GPS: Global Positioning System. 24+ satellites triangulate position to within meters.
GPS Technology
How satellite navigation determines location anywhere on Earth
GPS: US Department of Defense system, 24+ satellites in medium Earth orbit. Receiver needs signals from at least 4 satellites to calculate 3D position (latitude, longitude, altitude). Accuracy: civilian 3-5 meters, military better. GLONASS (Russia), Galileo (EU), BeiDou (China): other GNSS systems.
Mental Maps
Mental maps: internal geographic representations. Vary by individual, culture, and experience.
Mental Maps
How people mentally represent geographic space
Mental maps (cognitive maps): internalized, subjective representations of geographic space. Shaped by personal experience, media, education. Distance decay: knowledge decreases with distance from home. Upward distortion: home region often drawn larger than actual size. Stereotyping: regions reduced to simplified images.
Gerrymandering and Electoral Geography
Gerrymandering: manipulating district boundaries for political advantage — geography used as a weapon
Gerrymandering and Electoral Geography
How map-drawing determines political power
Named after Elbridge Gerry (Massachusetts governor, 1812). Packing: concentrate opposition voters in a few districts — they win big there, wasted votes elsewhere. Cracking: split opposition voters across many districts — they lose everywhere. Modern gerrymandering uses sophisticated algorithms. Supreme Court: political gerrymandering is a political question, not justiciable.
Spatial Analysis
Spatial analysis: asking geographic questions — where is it, why is it there, what patterns exist?
Spatial Analysis
The core analytical approach of geography
Geography asks spatial questions: location, distribution, pattern, association, interaction, change. Spatial autocorrelation: nearby things tend to be more similar than distant things (Tobler's First Law). Cluster analysis: identifying geographic concentrations. Buffer analysis: areas within a given distance. Overlay: combining multiple data layers.