Luis Carlos Ayala treks up and down hilly driveways in a local neighborhood on a recent weeknight, going door to door to deliver his short campaign spiel and a flier. Even though the 18,650-student Pasadena Unified district serves a locale of more than 202,300 residents, Mr. Ayala aims to reach voters in an area of only 28,900 for this race, as a result of the school district's recent switch from at-large elections--in which voters can cast ballots for any candidate--to trustee or "district" elections, in which voters select a candidate on the basis of where they live. Pasadena's election switch follows an increasing number of others in California school districts, influenced by the 2001 California Voting Rights Act, which prohibits localities from running at-large elections if they hinder minority groups from electing candidates of their choice. In the past few years, California has seen a number of lawsuits challenging local at-large election systems, a situation that has pushed school districts throughout the state to consider the racial and ethnic diversity of their boards and whether voting in their communities is racially polarized.