This dissertation empirically studies the economics of several recent important public policies in the United States, including the corporate tax cuts enacted by the Tax Cuts and Jobs Act of 2017; the Opportunity Zone program enacted by the same legislation; housing policy changes in the city of San Francisco; and tariffs enacted during the ongoing US-China Trade war. The chapters offer both causal and descriptive evidence and build on previous economic research in the fields of public finance, labor economics, and international trade. Overall, the dissertation highlights the importance of economic research in evaluating the tradeoffs inherent in setting policy and in empirically evaluating policy impacts.