5.1 Map Elements and Layout

Key takeaways

• A professional map has nine standard elements — each with a specific purpose.
• Layout is a deliberate hierarchy: the reader's eye should travel from title to message to supporting information.
• Skip elements only when you can justify the omission.

Introduction

Cartography is more than "putting data on a map". A finished map is a document that tells a story with numbers, colours, and geography, and every element on the page is either pulling its weight or getting in the way. This lesson covers the nine canonical elements and the layout principles that arrange them into something a reader can actually use.

The nine map elements

1. Title — tells the reader what the map shows. Should include the subject and, if relevant, the place and time. Bad: "Map 1". Good: "Residential construction permits issued, Copenhagen, 2023".
2. Main map — the data visualisation itself.
3. Legend — the key. Explains symbols, colour ramps, classification breaks. Absolutely mandatory whenever symbology isn't self-evident.
4. Scale bar — a graphical or text indicator of ground distance. A ratio (1:50 000) is fine for print, but a graphic bar remains meaningful when the map is resized.
5. North arrow — orientation indicator. Only necessary when the map is not north-up (it usually is) or when the audience includes non-technical readers.
6. Inset / locator map — situates the main area within a broader region. Crucial when the main map covers an unfamiliar area.
7. Data source and credits — where the data came from, when it was acquired, who made the map. An ethical requirement and a source of authority.
8. Projection and CRS — the projection used (and optionally the EPSG code). Essential for reproducibility and precise communication.
9. Date — when the map was made and, often, the data's vintage.

Additional optional elements: author bio, logo, colophon, index (for atlases), grid / graticule.

Layout as information hierarchy

Your map is a document. Readers scan in a predictable order: top-left → bottom-right for Western readers, top-right → bottom-left for right-to-left languages. Arrange elements to match:

1. Title at top.
2. Main map dominant — at least 60% of the page.
3. Legend adjacent to the main map, typically bottom-right or right.
4. Scale bar near the legend, often bottom-left.
5. North arrow unobtrusive (corner).
6. Credits small, at the bottom.
7. Inset in a corner that doesn't compete with the main map's key areas.

The canonical layout is also the boring one. Break from it only when the map's story demands (e.g., letting the main map fill the entire page for maximum emotional impact, with overlaid legend).

Visual hierarchy

Larger, darker, higher-contrast, and top-left items draw attention first. Use this deliberately:

• Title: largest type (18–36 pt).
• Main map features: strong saturation for the subject, muted for context.
• Legend and scale bar: smaller type (8–10 pt), reduced saturation.
• Credits: smallest (6–8 pt), often grey.

The viewer's eye should traverse: title → map → legend → details. If you can't trace that path in 2 seconds, revisit the hierarchy.

Figure-ground relationships

"Figure" is what the reader is meant to focus on; "ground" is the context. Cartographers deliberately push context back:

• Grey out background countries when showing a focal country.
• Use muted colours for land when highlighting water features.
• Add a subtle drop shadow around the main feature to "lift" it.

Strong figure-ground is what separates a memorable map from a cluttered one.

White space is content

Don't fill every square centimetre. Generous margins, breathing room around the title, and gaps between elements make the map easier to read. Common mistake: cramming a data source, date, and author bio into one tiny line at the bottom to avoid "wasting" space. The map gains clarity if those breathe.

Context elements: graticules and base maps

• Graticule — the lines of latitude and longitude drawn on the map. Appropriate for small-scale (large area) maps where global position matters; often omitted at city scale.
• Base map — streets, rivers, labels behind your data. Use muted, low-saturation base maps so your data pops. Tools: CartoDB Positron / Dark Matter, Stamen Toner, Mapbox Light.

Print vs digital considerations

Print:

• Fixed size and resolution; design for DPI (300 dpi minimum).
• Plan for paper colour shift (whites shift slightly yellow).
• Include a scale bar for true distance perception.

Digital (interactive):

• Design for multiple zoom levels.
• Tooltips, pop-ups replace some legend functions.
• Responsive layouts — legend may dock or float.
• Performance matters: rendering time, tile loading.

Atlas is a good place to test these digital choices quickly. Upload a small layer, style it, add a popup, and share the map with someone who has not seen the data. If they can understand the subject, legend, and key attributes without explanation, your layout is doing its job.

Common layout mistakes

• No legend for symbolised data.
• Title that doesn't name the subject, place, or time.
• Scale bar absent or in units inappropriate for the audience.
• Data source hidden in a 4-pt footnote.
• Colour ramp that implies ordering where none exists.
• North arrow for a clearly north-up map (redundant).
• Inset map positioned over important data in the main map.

Self-check exercises

1. Which three map elements are almost never optional?

Title, legend (when symbols aren't self-evident), and data source / credits. A map without these is hard to interpret responsibly and fails basic academic and journalistic standards.

2. When can you legitimately omit the north arrow?

When the map is north-up and the audience will understand that from context (typical for professional and general audiences). Arrows are essential when the map is rotated, oriented to something other than true north, or when the audience is unfamiliar with mapping conventions.

3. Your main map fills 80 % of the page, but the legend is squashed into a tiny corner. What's the fix?

Rebalance the hierarchy. The main map can shrink slightly (say 65–70 %) to give the legend room to breathe; or the legend can float over a less-important area of the map with a subtle white background. Readers shouldn't have to squint to decode symbols.

Summary

• Nine canonical elements: title, map, legend, scale, north arrow, inset, source, projection, date.
• Layout is information hierarchy — scale, contrast, and position together route the reader's attention.
• Figure-ground relationships make the subject stand out.
• Omit elements only deliberately, not by oversight.

Further reading

• Brewer, C. — Designing Better Maps.
• Slocum et al. — Thematic Cartography and Geovisualization.
• Tyner, J. A. — Principles of Map Design.
• CartoDB blog — Map design best practices.