Several of the principle colors include:

• Blue: lakes, rivers, streams, oceans, reservoirs, etc.
• Red: major highways, roads, urban areas, airports, special interest sites, military sites, place names, buildings, borders.
• Yellow: built-up or urban areas.
• Green: parks, golf courses, forest, orchards, highways.
• Brown: deserts, historical sites, national parks, military reservations or bases, contour (elevation) lines.
• Black: railroads, highways, bridges, place names, buildings, borders.