Just posted on SSRN: Aghion, Philippe, Alesina, Alberto F. and Trebbi, Francesco, “Choosing Electoral Rules: Theory and Evidence from US Cities” (March 2005). Harvard Institute of Economic Research Discussion Paper No. 2065. Here is the abstract:

This paper studies the choice of electoral rules, in particular the question of minority representation. Majorities tend to disenfranchise minorities through strategic manipulation of electoral rules. With the aim of explaining changes in electoral rules adopted by US cities (particularly in the South), we show why majorities tend to adopt “winner-take-all” citywide rules (at-large elections) in response to an increase in the size of the minority when the minority they are facing is relatively small. In this case, for the majority it is more effective to leverage on its sheer size instead of risking conceding representation to voters from minority-elected districts. However, as the minority becomes larger (closer to a fifty-fifty split), the possibility of losing the whole city induces the majority to prefer minority votes to be confined in minority-packed districts. Single-member district rules serve this purpose. We show empirical results consistent with these implications of the model.