Symbol Systems

Part of Cartography & Surveying

How to design and use consistent map symbols to represent real-world features clearly and unambiguously.

Why This Matters

A map symbol is a visual code. It stands in for a real-world feature — a spring, a mill, a road — in a form small enough to fit on paper and clear enough to read at a glance. Symbols are the vocabulary of cartography, and like a language, they only work if both the mapmaker and the map reader share the same understanding.

When a community uses consistent symbols across all its maps, anyone familiar with the system can read any map produced in that community. Visitors and traders can navigate. People who survey an area different from the one they normally work in can still contribute to the same system. Future generations can read the historical record.

Symbol systems take investment to establish but pay off continuously in reduced confusion and more efficient map use. The effort to standardize early — rather than having each mapper invent their own symbols — is worthwhile.

Principles of Good Symbol Design

Intuitive visual connection: Good symbols look like what they represent, or have an obvious visual logic. A tree symbol looks tree-like. Water is shown in blue (where color is available) or with horizontal hatching. Roads have parallel lines. When intuition supports the symbol, less explanation is needed.

Scalability: Symbols must be legible at the map’s working scale. A symbol that looks good at 10 cm becomes a blob at 1 cm. Design or test symbols at the actual printing size. Simple symbols survive scale reduction better than complex ones.

Discriminability: Symbols that are too similar will be confused. A point symbol for a well and a point symbol for a spring should look visually distinct even in poor light or at small size. Geometric symbols (circle, square, triangle, star) are highly discriminable. Similar shapes with different fills (solid versus open) are moderately discriminable. Avoid more than 5–6 visually similar symbols in a single category.

Consistency: The same symbol should always mean the same thing on any map produced by the same community. Inconsistency — even for good reasons on a specific map — erodes trust in the whole system.

Categories of Map Features

A complete symbol system covers at least these categories:

Natural features:

• Water: streams, rivers, lakes, ponds, springs, wells, marshes
• Terrain: cliffs, escarpments, sand, bare rock
• Vegetation: forest, scrub, grassland, orchard, isolated trees

Built features:

• Buildings: residential, commercial, industrial, religious, agricultural (barn, stable, mill)
• Infrastructure: roads (by type), paths, tracks, bridges, fords, ferries
• Boundaries: property lines, administrative limits, field boundaries

Land use:

• Cultivated fields, gardens, waste ground
• Quarries, pits, dumps

Special features:

• Benchmarks and survey controls
• Danger zones (cliffs, flood areas, mined ground)
• Resources (mineral deposits, timber areas, water sources)

Constructing Point Symbols

Point symbols represent features that are too small to show at scale. They are centered on the feature’s actual location (or at the base of the symbol for tall features like trees and towers).

Geometric base shapes:

• Circle: natural features (spring, sinkhole, isolated tree)
• Square: built structures (building types distinguished by fill — solid, half, open, hatched)
• Triangle: elevated features (benchmark, triangulation point)
• Diamond: minerals, resources
• Cross or asterisk: special facilities (hospital, place of worship)

Fills and variations: A solid circle = spring. An open circle = well. A circled dot = borehole. This system of variations within a shape family allows a small number of base shapes to cover many distinct features while remaining visually related.

Size: Point symbols typically range from 2 mm to 5 mm at the final print size. Larger than 5 mm and they obscure nearby features; smaller than 2 mm and they become unreadable.

Line Symbols

Lines represent features that are linear at map scale: roads, paths, rivers, boundaries.

Line weight: Heavier lines are more important. Main roads heavier than paths. Rivers heavier than drainage ditches. Boundaries heavier than internal field lines. Typical weights: 0.2 mm for minor features, 0.4 mm for secondary, 0.7 mm for primary.

Line style: Solid lines are firm and accurate. Dashed lines suggest uncertainty, administrative boundaries, or proposed features. Dotted lines for underground features or inferred lines. Dash-dot for administrative limits.

Double lines: Wider roads are shown as two parallel lines with the interior left empty or paved with a stipple pattern. Narrower paths are single lines.

Color coding (where feasible): Blue for water, brown for contours and soil features, black for man-made features and roads, green for vegetation, red for important annotation or danger. Even if full color is unavailable, reserving different pens for different line types simulates some of this differentiation.

Area Symbols

Areas filled with characteristic vegetation, land use, or terrain type are shown with consistent hatching or pattern fills.

Standard conventions:

• Horizontal lines: water bodies (when blue ink is unavailable)
• Irregular dense hatching: forest
• Scattered dots: sand or gravel
• V-shapes: marsh or reeds
• Close regular dots: built-up area
• No fill (white): cultivated land or open ground (the default)

Boundaries: Area symbols need clear boundaries. Where two areas meet, one boundary line serves both. The boundary line type indicates the type of division: fence, stream, road, administrative limit.

Density: Area symbol density must be distinguishable from similar patterns at the map’s working scale. A marsh pattern and a forest pattern that look distinct when drawn large may become indistinguishable at small scale.

The Map Legend

Every map must include a legend (or key) explaining every symbol used on that specific map. Even if a community has a standard symbol set, not every map uses every symbol. Show only the symbols present on this map.

Legend layout:

• Group symbols by category (natural, built, boundaries)
• Show each symbol at actual map size with a short, clear label
• Place the legend in a consistent location — bottom left or bottom right corner, inside the map border or in a box outside the border

Test your legend: Give a draft map to someone who was not involved in making it. Ask them to find specific features using only the legend. Where they struggle, the symbol is ambiguous or the legend explanation is unclear.

Adapting Standard Systems

Existing national and military topographic symbol conventions represent centuries of refinement and testing. Where copies of such standards are available — in pre-collapse topographic maps, military manuals, or surveying textbooks — adopt them rather than inventing from scratch. Minor adaptations for local conditions (a symbol for a specific crop type or a local building style) can be added to the standard set, clearly documented, without disrupting the inherited conventions.

When no standard is available, document whatever symbol system your community adopts in a written standard, reproduce it in the front matter of every map collection, and update it deliberately rather than allowing informal drift.