BrownVTrumpOilMap.com

An interactive map of oil drilling permits across California, plotted against the administrations that approved them. Thousands of wells, on one surface, with the permit record behind every point.

Why a map rather than a chart

A table of permit counts is an argument you have to accept. A map is one you can check. When somebody sees a cluster of new wells inside a neighbourhood they recognise, the argument makes itself, and the reaction is qualitatively different from reading the same figure in a sentence.

That is worth the considerable extra engineering, and it is the reason this exists as a standalone property rather than a section of another site.

The cartography problems nobody warns you about

Thousands of points in a state-shaped area means most of them overlap at any useful zoom. Clustering solves the rendering and introduces a new problem: a cluster labelled "1,429" is a number, not a place, and the entire persuasive value was in seeing where things are. Getting the zoom thresholds right — when a cluster becomes wells, and how fast — is most of the design work.

The other trap is baseline. A map showing every well ever drilled is a map of California's history and proves nothing about any particular administration. The framing has to be explicit about date ranges and about what is being compared, on the page, where a sceptical reader will see it.

Keeping it honest

Permits are public record, and the map states its own coverage dates rather than implying it is live to the minute. A visualisation that looks current and is not is the failure mode that costs an advocacy organisation its credibility, and it is invisible until somebody checks.