Theorists have long argued that democratic policymakers respond to political pressures from their constituents. Although empirical work generally supports that broad contention, heterogeneity prevails both in theoretical work and empirically across country-times over exactly what comprises the constituency to which policymakers respond. We propose conceiving the potential bases of democratic representation as a continuum from the interests of the policymaker's geographic constituency, her electoral district, d, to those of her party's supporters, her partisan constituency, p. The effective constituency, c, to which democratic policymakers respond would then be some convex combination of these partisan and geographic extremes, with the partisan weight summarized by the degree to which parties are able to act as strategic units and receive their electoral support as units, i.e., of party unity, u. That is, heuristically, we conceptualize c=u*p+(1-u)*d. Re-examination of the familiar Weingast-Shepsle-Johnsen (WSJ) model of distributive politics and pork-barrel spending (the law of 1/n) motivates the analysis and undergirds empirical evaluation of our conception of the effective constituency. Postwar histories of public spending and distributive politics in developed democracies seem not to support a pure-electoral- district WSJ model, but postwar public spending in the United States, where data best-suited to evaluate the argument exist, does support a WSJ model as modified to reflect our conception of the effective constituency. We conclude with some ideas for extending the basic effective constituency notion beyond partisan and geographic bases of representation and for incorporating more explicitly and directly into empirical specification of public-policy models certain theoretical propositions that purport to explain aspects of the political-economic institutional, structural, and strategic context, such as the degree of party unity, that shape how policymakers allocate their efforts across public-good, redistributive, distributive, and rent-seeking activities. We consider several such arguments relating political-economic institutional, structural, and strategic contexts to the degree of party unity and of geographic versus partisan representation, and thereby to policymakers' weight on each type of policy activity, and show how to embed and test such arguments within estimable empirical models of public spending using the effective constituency concept.