This research seeks to explain patterns of capital investment and operating expenses for urban transit systems in the United States. We isolate supply factors including urban scales, urban spatial form and financial capacity. Individual and group transit demands are accounted for by social and demographic characteristics including education level, immigrant populations, poverty levels, senior population and race. The results demonstrate that transit investments are super-linear to population, directly contradicting predictions of Bettencourt’s popular urban scale theory. Transit expenses are explained primarily by urban scales, urban spatial form and financial capacity, but demand forces such as poverty, car usage and political ideology have strong effects as well.