Malapportionment and Ideological Bias in Chilean Electoral Districts

In 2015, Chile fundamentally reformed the electoral system it had used since 1989. The old system was characterized by high levels of malapportionment, or differences across districts in the ratios of voters to representatives. In the first elections after redemocratization, malapportionment favored the ideological right, but elections since 2000 have yielded no evidence that malapportionment produced ideological bias. The new, postreform electoral system reduces malapportionment in the lower chamber, although it remains pronounced in both chambers. Nevertheless, analysis of results from previous elections, coupled with information about the new districts, suggests that, consistent with recent experience, malapportionment will not produce ideological bias in elections to either chamber.