Before revision:  Although bus ridership is declining across neighborhood characteristics, these results suggest that the underlying cause  must be primarily affecting the travel behavior of white bus riders . Shifts in neighborhood socio-demographics, however, were found to be modest and unlikely to be causing the nation-wide ridership crisis.
After revision:  Although bus ridership is declining across neighborhood characteristics, these results suggest that the underlying cause of bus ridership decline must be primarily affecting the travel behavior of white bus riders . Shifts in neighborhood socio-demographics, however, were found to be modest and unlikely to be causing the nation-wide ridership crisis.