Methodology & source manifest
Everything on the Department of Transportation monitor derives from public records — the DOT FY2027 Budget Highlights “Budgetary Resources Table”, OMB's Historical Tables, the USAspending API, and reachable DOT OIG / GAO reports. This page is the audit trail: method, sources, validation, and every flag.
Method
Trust-fund / oblim vs discretionary — why the structure is led, not flattened
DOT does not fit a plain discretionary-budget-authority frame. The bulk of its program funding is Highway Trust Fund contract authority controlled by annual obligation limitations — money the FY2027 Budget Highlights classes as mandatory, not ordinary discretionary BA. Of the FY2027 $114.1B in total budgetary resources, only $26.8B is gross discretionary budget authority; the ~$87.3B mandatory subtotal is overwhelmingly the trust-fund / obligation-limit mass (FHWA's Federal-Aid Highways, FTA's Transit Formula Grants, the FMCSA / NHTSA grant lines). This monitor leads with that distinction and keeps the two frames strictly separate: obligation limitations and discretionary BA are never summed into one “budget” number as if equivalent. Each account carries the source's own funding-type tag (D / M) and fund source (GF / TF / SF, OBLIM).
What validates, and the honest flags
The budget spine validates to the dollar: every keyed account row sums to its administration's published base Total; the administration base Totals sum to the published total budgetary resources; and the after-offsets breakdown (non-defense discretionary + defense discretionary + mandatory + repurposed IIJA advance appropriations) ties to the published total budgetary resources after offsets — per fiscal year (FY2025 / FY2026 / FY2027). Any miss beyond the document's own documented $1-thousand rounding throws at build time; each $1 rounding artifact the source itself carries is flagged below, not silently absorbed. The per-administration “Total Budgetary Resources” rows add the one-time IIJA and disaster-relief supplementals on top of the base; those are carried separately, never folded into the base total.
Source documents & validation ledger
The history layer is shown in nominal dollars only — OMB Historical Table 5.2 publishes no constant-dollar basis, and no deflator is synthesized. It is agency-wide budget authority, a different construct from the Budget Highlights total-budgetary-resources / discretionary-BA frames; the two are never conflated.