Cheap power, thin coverage: reading the Supercharger economics map like a site scout

The US Supercharger Economics Map draws two datasets on one canvas: every US Tesla Supercharger as a dot, and every utility territory with a modeled tariff colored by its derived effective electricity cost per dispensed kWh. Each layer is informative alone. The reading that only exists when they overlap is the site scout's question: where the dots are dense, where they are sparse, and what the power costs in each place. This post is a walk through that reading as the map stands today — 3,167 stations, 85 filed rate rows across 49 states and DC, 51.8% of stations sitting in a priced territory. Nothing here is advice; it is a description of what the two layers show when read together.

What "effective cost" folds in#

The color is not a retail rate. It is the derived cost per kWh actually dispensed to vehicles under each utility's currently filed tariff, at one fixed reference operating profile — the same profile for every territory, with time-of-use windows, demand-charge structure, riders, and charging losses folded in. That normalization is what makes territories comparable: the color differences come from rate design, not from differences in the assumed site. The full profile is stated next to the map's legend and on the methodology page.

The inversion the overlay shows#

Sorting the priced territories by effective cost and counting the dots inside each one produces a pattern that holds across most of the map: the cheapest territories are the emptiest.

The median priced territory holds 8 stations. Meanwhile the densest territory on the map — PG&E, with 302 stations — carries an effective cost near 28.9¢/kWh, close to double the cheapest rows. Southern California Edison follows at 164 stations and ~30.4¢. The two layers largely anti- correlate: station count tracks population and highway traffic, and the tariff a station lands on is whatever utility happens to serve that ground. Charging infrastructure was mostly sited on demand; the electricity cost came with the territory.

The exceptions are the interesting part#

Two territories break the pattern in the same direction: Commonwealth Edison (Chicago) prices near 16.0¢/kWh with 51 stations inside it, and Dominion (Virginia) near 16.3¢ with 59. Both combine major-metro traffic with rate designs that land at a quarter of the map's top end. At the other extreme, the corridor states of northern New England price above 80¢/kWh at the reference profile — Green Mountain Power near 87¢, Central Maine Power near 95¢ — and Hawaii's territories sit past $1.10.

The spread across the priced map is roughly 7× end to end. For context, the three territories added this week — Philadelphia's PECO (~49.5¢), JCP&L in northern and central New Jersey (~40.4¢), and Duke Energy Florida on the Tampa–Orlando corridor (~39.7¢) — all land in the upper half of that range, and all three had dense dot clusters sitting gray until their filed tariffs were derived.

What the map cannot say#

Half the dots still sit in named-but-unpriced territories (46.4% today); those territories are gray because their filed rates are not yet modeled, not because rates there are unknowable — the map fills in as derivations land. And a territory's color is computed at the reference profile: a specific site's stall count, utilization ramp, and rate-schedule eligibility move the number, which is what the scenario model computes per address. The per-territory rate structures behind the colors are browsable in the demand-charge lookup, and the covered jurisdictions are ordered by charging economics in the utility rankings.

Every rate behind the map is digit-checked against the utility's own filed sheets, and each territory records the filed source and its next scheduled rate change. The map page states the derivation date of the bundle it renders — the freshness stamp is part of the data.