Dublin experienced a marked stagnation in population growth in the second half of the nineteenth century, accompanied by decaying infrastructure and poor public health. Historians have emphasized that this crisis was coupled with poor governance of the city of Dublin-manifested by eroding public services together with increasing tax burdens to counteract growing debt. This paper studies the municipal boundary expansion of Dublin in 1901, which occurred as a way to alleviate the city's financial distress. It saw multiple relatively wealthy townships annexed by the city via royal order to increase Dublin's tax base. Using a sample of census records matched to city streets, we show that wealthy residents and Protestant residents were more likely to leave annexed areas compared to areas that remained independent. Moreover, we offer anecdotal evidence that at least some of the wealthy Protestant households departing annexed townships sorted into jurisdictions that remained independent. Our findings offer support to arguments that the municipal annexation by the city of Dublin may have accelerated the decline of annexed areas in the early twentieth century and contributed to municipal fragmentation in metropolitan Dublin.