How to Read Terrain Clues for Borders

A mountain ridge, a river bend or a familiar coastline can help you place a border on a map. None of them guarantees the exact answer: boundaries can follow surveys, older river courses or agreements that are invisible in the terrain. This guide helps you make a useful first attempt, then learn from the reveal.

Each example opens an untimed practice question. You can try it again without changing your daily challenge score.

1. Orient the map before drawing

Read both names in a shared-border question. Look for a coastline, a large lake, a city or a mountain range you recognise, then decide which side each neighbour occupies. The map stays north-up; use its scale bar to judge the size of a bend or gap. A broad landmark can tell you where to begin even when it is not part of the boundary.

On a phone, two fingers move and zoom the map; on a computer, use the Move control or hold Space while dragging. Switch back to Draw before tracing. If a clue is missing at one zoom level, move or zoom to see whether the surrounding terrain gives you a better reference.

2. Use ridges as clues, not as a ruler

Shaded relief makes high ground and valleys easier to distinguish, but shading is not a border layer. A watershed may help you predict part of a boundary while its turns and endpoints still need to be remembered. Do not assume that a line runs through every summit.

Try it: in Nagano–Gifu, look for the Japanese Alps and sketch the direction of the boundary. After submitting, look at the blue answer line: was your line near the correct mountain belt, and did it extend far enough?

Try another: in Norway–Sweden, orient yourself with Norway’s western coast before using the inland mountains. At this larger scale, getting the location and overall direction right matters before refining individual turns.

3. Rivers and lakes can locate a question

Rivers often make memorable landmarks because their bends are distinctive. In Indiana–Kentucky, start with the Ohio River. Follow the general bends, but check the reveal: a boundary in the game’s source data need not fall exactly on the visible centre of today’s river.

A lake can be useful even when it is not the boundary. Shiga–Kyoto is a good example: Lake Biwa is inside Shiga, and Kyoto lies to the west. Find the lake to orient yourself, then look beyond its shore for the prefectural line.

Similarly, the Mekong provides clues for parts of Laos–Thailand; do not assume a river marks every kilometre of a long border.

4. For a straight line, placement matters

Some surveyed boundaries are nearly straight even where the landscape is not. In Colorado–Wyoming, first estimate where the line sits between the surrounding states and where it begins and ends. A perfectly straight line in the wrong place will still score poorly because the game compares geographic position, not just shape.

5. Turn the result into a second attempt

For a shared border, On the line describes how closely your drawing follows the answer; Border covered describes how much of the answer you followed. A short accurate stroke can have high precision but low coverage. For example, if those values were exactly 90% and 30%, their harmonic mean would be 45 out of 100. The result also shows the distance tolerance used for that question.

For an outline, green shows overlap, orange shows missed land and red shows extra land. Compare whether you placed the region correctly before worrying about small bends. Press Try again, change one thing—such as an endpoint or the size of the outline—and compare the next reveal. The scoring guide explains the calculation and the treatment of sea and islands.

About the maps and sources

The game uses shaded elevation, water and simplified boundary data; it is a learning game, not a navigation or surveying map. The map data page lists the source and licence for every pack. For background on the landmarks above, see the Indiana environmental agency’s description of the Ohio River, Shiga Prefecture’s geography overview and the Mekong River Commission’s river map.

If a boundary or clue looks wrong, use the report link on a result or contact us with the question. See how to play for the controls and daily rules.