With nationwide declines in public transportation ridership, transit may be falling behind in its ability to help cities deal with congestion. Increasing real-estate values are causing the economic displacement of low-income populations, those most closely associated with transit ridership. A plethora of new mobility options are providing alternatives for transit riders who can afford them and even for those who require subsidy. But how will access to transit, ridership, and congestion be impacted by these shifts in demographics and the introduction of new mobility services? In thrust 1, the team assessed the impacts of low-income individuals and families moving to the periphery of communities, i.e., the suburbanization of poverty, on public transit. In addition, this thrust provided a detailed analysis of sociodemographic and accessibility changes over time. In thrust 2, the study team developed a novel approach to understand how levels of transit service and demographics impact transit ridership on a highly specific spatial and temporal scale. In thrust 3, the study team developed a better understanding of the interactions between public transit and transportation network company (TNC) providers. In thrust 4, the study team documented the rapid evolution of paratransit services available to access healthcare. Although the research in all four thrusts focused on specific areas of the southeast US, the results are applicable nationally to aid transit and regional planning agencies.