Album de Statistique Graphique - Recettes des Tramways de la Banlieue de Paris en 1878. (Receipts of the trams of the suburbs of Paris in 1878) [12511.019]
The pattern
This still is filed under Data as proof.
Define
A chart, map, or count that is the argument, not an illustration next to the argument.
Mechanism
Sighted evidence. The reader is asked to believe their eyes: a bar, a share, a spread on a map.
Verdict
The claim is comparative or quantitative and the figure can be read without a caption doing the sell.
Why it works
Putting the value on the line's own stroke instead of in a bar chart beside the map keeps route and revenue in one mark, so the reader sees profitability as a property of geography. The grey survey base is pushed almost to invisibility and the pink city wash reads as area rather than detail, which frees the full colour range for the only variable that matters. The table is not redundant: the ribbons rank the lines instantly and the table settles arguments, which is exactly the division of labour a minister reading a plate before a meeting needs.
Steal this when
Use it when performance is attached to a route, a territory or a physical network and the client keeps discussing the network as a list. Weighting the line by the money makes an underperforming branch visible without anyone having to name it in the meeting.