Seeking to improve low voter participation in special elections, the California Assembly on Thursday narrowly passed and sent to the Senate legislation that distribute all ballots by mail for elections to fill vacancies. The constant shuffle of elected officials seeking new seats follows a familiar pattern — a state legislator resigns or wins election to a new office, and a tiny sliver of the electorate chooses a replacement. Turnout in a recent pair of special elections hovered around 12 percent and 8 percent, respectively. Citing the expense, the Senate leader floated letting the governor fill vacancies. An effective solution, according to proponents of Assembly Bill 1873, is to make mailboxes, not polling places, the nexus of special elections.