The thesis
Regulation requires the state to specify what behavior is permitted and enforce compliance. Pricing requires the state to specify what the externality costs and let markets adjust. Pricing is simpler and more effective at the margin. The Externality Limiter prices the ten major documented externalities and routes their revenue per a small set of architectural rules.
Pricing carbon is progressive — by design. The carbon fee falls on consumption, but the rebate is per capita: every adult receives the same FedCard credit ($160/ton-equivalent cap). High-emission households pay more in fees than they receive in rebate; low- and middle-income households receive more than they pay. The instrument prices the harm at source while shifting net dollars toward households with less capacity to pay. The same logic carries the VAT pre-bate on the consumption side of Engine 1.
The ten externalities, ordered by importance
How transportation gets paid for
The mileage-weight fee replaces the federal gas tax. It bills the accelerated damage portion — pavement wear scales with the fourth power of axle load, so heavy commercial vehicles cause roughly 9,600× the marginal damage of a passenger car while paying roughly 4–5× under fuel-tax-based financing — and it sits alongside continuing user payments from all road users. Transportation overall remains subsidized from the General Fund: roads, buses, light rail, longer-distance rail, aviation, and waterways are public infrastructure with broad civic returns that user fees alone never cover.
User fees do one thing well: they shift behavior at the margin. Pricing damage at source moves long-haul freight toward rail and intermodal where those modes are cheaper to society. Layering congestion pricing on top shifts when trucks move — slow, lighter, automated runs at night rather than peak-hour heavy convoys — without legislating the schedule. The fee structure does the steering; the General Fund does the building.
Full transportation architecture → — gas-tax replacement, weight × speed × congestion fee, default-to-maximum enforcement, transit parity rule, autonomous-light-freight optimization, modal equity table, and the 20-year state-of-good-repair budget.
Two ring-fenced trusts only
The Accord deliberately limits ring-fenced trusts to two — the Climate Adaptation Trust and the Financial Stability Reserve — because both are obligations whose timing is unknowable but whose occurrence is near-certain over the relevant horizon (multi-decade physical climate risk; recurring multi-decadal financial-stability events). Both require capital pre-positioned so the response is mechanical rather than political. Each has its own dedicated page; the trust mechanics do not need to be repeated here.
Every other priced externality (water, health-risk, road-use, IIE, FTT, interchange, parity wedge) flows to the General Fund alongside every other federal receipt. The architecture deliberately avoids trivial earmarks.