Regional transportation plans describe comprehensive planning processes and visions, but long-range transportation planning is only one among many decision sites for transit investment. As most plans are only partially implemented, this research aims to illuminate the factors that determine which transit projects are implemented. It combines case study research (Miami, Orlando, and Boston), with quantitative analysis of federal transit funding. The work addresses three broad questions about metropolitan decision making and action: how does significant action happen across jurisdictions? What is the state and federal role in metropolitan governance? How does equity fare in implementation? In each of three papers, I start at a different government scale: metropolitan planning organization (MPO), state, and nation. The first paper describes critical decision making processes external to MPO planning. Case studies of Boston and Miami demonstrate that MPO planning responded to, rather than determined, transit implementation choices. Due to the influence of external decisions or bypasses, I argue federal directives for equity in regional transportation planning were insufficient to advance equity in Miami and Boston. Community mobilization in Boston was sustained and moderately successful; advocacy groups advanced two projects toward implementation. Next, I examine the sub-national state's role in transit implementation, based on projects proposed in Miami and Orlando. The Florida Department of Transportation adopted a leadership role for projects that had greater economic significance and regional consensus behind them. By selectively contributing capacity, -power to,[DOUBLE VERTICAL LINE] state actors exerted -power over[DOUBLE VERTICAL LINE] regional outcomes in Orlando and Miami. The third paper presents a quantitative analysis of the federal New Starts program, which funds transit expansion. Local financial commitment most correlates with federal funding, according to statistical results. All funded projects met a minimum threshold of benefits. Yet, the Federal Transit Administration was not more likely to fund projects with higher benefits ratings. Findings suggest regionally significant action happens not simply nor easily through planning, but instead through established government entities and through the mobilization of capacity. Altshuler and Luberoff's -bottom-up[DOUBLE VERTICAL LINE] federalism is a useful concept to describe how powerful federal actors respond to and enable action at smaller scales. In this conceptual frame, local initiative and mobilization are pivotal, aligning with increasing interest in governance. At the same time, however, findings indicate the need to further develop governance as an analytic category that incorporates multiple types of power and spheres of action. In addition, this research shows that equity advocates can sometimes affect outcomes. Due to existing constraints for metropolitan planning organizations, the conclusion describes options to strengthen or alter their role. I conclude with reflections on the ideal rail deal. Political will behind infrastructure investment can be an opportunity to enable other critical environmental and equity interventions.