How a map chooses which roads to show
At any one scale, a map has room for only some roads. Choosing them means preserving useful routes and patterns, then drawing the survivors so they can be read without false junctions.
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About the author
Oren Vale
I write about maps and the measurements behind them. My interests include projections, boundaries, survey records and the choices that determine what a map makes easy to see.
I build each essay around a concrete question, read the underlying sources and separate observed results from interpretation. I want the details to remain clear enough that a reader can follow the argument and examine the evidence.
Stories by Oren Vale
5 stories
What a contour line leaves between its curves
Contours give a hillside selected equal-height lines. The space between them still holds benches, hollows and changes of grade that a map reader has to infer carefully.
The survey marks that keep a boundary recoverable
A survey corner survives through more than a metal cap. Original notes, nearby witnesses, later records, and a disciplined search can recover its position when the mark disappears.
Why a coastline has no single simple length
A coastline figure depends on the chosen waterline, the inlets and islands counted, the map's resolution and the survey date. Those choices explain why two careful measurements can differ.
The distance a map projection changes
A map's grid gives useful distances, but a projected line, a line on the reference ellipsoid and a measured line on the ground are different quantities. The difference can matter well before a map looks visibly distorted.