This paper measures and analyzes explicit returns to United States firms through lobbying efforts and motivated expenditures at the federal level. The dependent variables of interest in this analysis are unrecognized tax benefits and adjusted marginal tax rates. Using a combination of multiple linear regression and system/dynamic generalized method of moments analysis on a panel of firm level data, I find statistically significant and economically substantial beneficial returns to the dependent variables for firms upon increase in annual lobbying expenditures, particularly when such firms are more profitable. New contributions to the empirical investigation of lobbying include the use of previously unexplored and updated variables of interest for firms and public policy considerations; modeling and computation successfully addressing endogeneity, reverse causality, and autocorrelation concerns in prior quantitative research; updated time frames for observed data; and improved robustness checks of models to demonstrate the persistence of computational results. The implications of the results for theoretical explanations of lobbying, perspective on U.S. lobbying, and possible implications for policy are investigated and found to offer support for public choice analyses of political behavior in that the new results are consistent with models explaining lobbying primarily as a result of self-interested behavior and rent-seeking efforts from agents.