Map skills for GED Social Studies

Read the frame of the map first

Before you look at the shapes and colors, find the information around the edges. Pay special attention to the legend: two maps of the same country can look alike while measuring different things, such as total population and population growth.

• Title: the topic, the place, and often the year.
• Legend or key: what each color, symbol, line, or pattern stands for.
• Compass rose or north arrow: which way is north. On most maps north is at the top, but check.
• Scale: how distance on the map compares with distance on the ground.
• Inset: a small extra map that shows a far-off area, such as Alaska or Hawaii, or a close-up of a crowded region.
• Source and date: where the data came from and when, which matters on historical maps.

Latitude and longitude

Latitude and longitude form a grid that gives every place an exact address. Lines of latitude run east and west around the globe but measure distance north or south of the equator, which is 0°. Latitude goes up to 90° at the North and South Poles. Lines of longitude run from pole to pole and measure distance east or west of the prime meridian, which is 0° and passes through Greenwich, England. Longitude goes up to 180°.

Coordinates are written with latitude first, then longitude, each with a direction: 40° N, 75° W. Places in the continental United States have north latitudes and west longitudes, and in that region a larger west longitude number means a place is farther west. One degree of latitude covers about 69 miles.

Measuring distance with a map scale

A scale can appear in three forms. A bar scale is a short line marked in miles or kilometers. A verbal scale states the relationship in words, such as “1 inch represents 50 miles.” A ratio scale, such as 1:100,000, means one unit on the map equals 100,000 of the same unit on the ground, whether the unit is inches or centimeters.

To find a real distance, measure on the map, then multiply by the scale. If the map is on screen and you cannot measure in inches, compare the distance with the length of the bar scale: a route about three bar lengths long, on a bar marked 0 to 100 miles, is about 300 miles.

Thematic and historical maps

A political map shows borders, countries, states, and cities. A physical map shows landforms and water, often using color for elevation. Most GED map questions, though, use thematic maps, which show one topic across a region.

• Choropleth map: areas shaded by a value, usually darker for more. Each shade covers a range, not an exact number.
• Dot density map: each dot stands for a set number, such as 10,000 people, so clusters show where something is concentrated.
• Proportional symbol map: circles or other symbols sized by amount, such as larger circles for bigger cities.
• Flow map: arrows show movement of people, goods, or troops, and a thicker arrow means a larger amount.
• Historical map: shows a place at a past date. Compare two dates to see what changed, such as territory added or borders redrawn.

Avoiding common map traps

Every flat map distorts the round Earth in some way. The Mercator projection, common on wall maps, keeps directions accurate for navigation but stretches areas near the poles. That is why Greenland looks about as large as Africa on it, even though Africa is roughly fourteen times larger. If a question compares the sizes of regions, be careful about judging by eye on a world map.

As with any source, eliminate choices that may be true about the world but are not shown on this map.

• Confusing a rate with a total: a state shaded dark for unemployment rate may still have fewer unemployed people than a large, lightly shaded state.
• Treating a large area as a large population: big, empty regions take up space on a map but may hold few people.
• Ignoring the date: a map from 1850 shows borders and territories that no longer exist.
• Assuming cause: a map can show that two patterns overlap, but it cannot prove that one causes the other.