During 2013, San Mateo County, California, will redraw its county supervisor districts. All counties in California except San Francisco County have five county supervisors, who comprise the county’s legislative body. See this story. It is very rare for mid-decade redistricting to occur. San Mateo County redrew its supervisorial districts after the 2010 census already. But the county’s system of electing supervisors has since then changed (as a result of a decision of the voters in 2012) from at-large elections with a requirement that one supervisor be a resident of each district, to a system in which each district elects its own supervisor. The change makes the district boundaries more significant. The new districts will be in place for the 2014 election.