Concentrated benefits and diffuse costs create an electoral incentive: constituents can readily credit the member for a local project, while each national taxpayer bears only a small share of its cost. That structure can encourage spending even when the national benefit is disputed.

Localized spending is not automatically wasteful. A bridge, research center, or flood project may serve a legitimate national purpose. Evaluation requires costs, benefits, selection criteria, and alternatives rather than the geographic concentration of benefits alone.

Pork barrel is an analytic or critical label, not a type of bill with a unique constitutional procedure. An earmark may deliver the benefit, and logrolling may assemble votes for the package, but those concepts describe different features of the politics.

Video lesson: How a Bill Becomes a Law: Crash Course Government and Politics #9