Progressivity of the personal income tax schedule, including top marginal rates, bracket spread, and targeted credits (EITC-equivalents).
General government spending as share of GDP, excluding transfers already captured under fiscal.transfer_expansion to avoid double-counting.
Ratification of the 16th Amendment in February 1913 removed the constitutional barrier to unapportioned federal taxes on income, and the Revenue Act of 1913 translated that power into a permanent graduated federal income tax. The initial schedule was modest by later standards, but it created an entirely new fiscal base for the federal state and shifted revenue capacity away from heavy dependence on tariffs and excises toward a more explicitly progressive direct-tax instrument.
Per invariant 3, reforms are scored by what they did on each channel-separated axis, not by the party that enacted them. This fingerprint is how the policy-match engine finds historical analogues.
Explicit links are curated by the author. Inferred links are hypotheses in the library that test the same axes this policy moved — the framework's answer to "what does the data say about a policy like this?".
Ranked by axis-fingerprint overlap with this policy. Direction match bolded — those are the closest historical analogues. Shape of the match is what drives policy-outcome comparison, not the country or party label.