We analyze the evolution of the spatial distribution of ridership in Chicago's Elevated Train over the last two decades, by means of station-level average daily passenger entries and census data to establish links between ridership changes and urban processes. Overall, we observe that 2007-2008 ridership was slightly below 1989-1990 levels, but recovering since the late 1990s. Ridership gains have shown a strong tendency to concentrate within a 10 kin radius from the CBD. Outside of this area, losses since 1989-1990 have been steady. The ridership recovery and its spatial distribution appear, therefore, to be related to an acceleration of urban processes, i.e., gentrification, immigration, employment concentration in the CBD.