California state Senators are elected every four years. The terms are staggered; those from even-numbered districts elected in one statewide General Election, and those from odd-numbered districts two years later. This creates a problem when district lines are redrawn every ten years. All of the new district lines for the state Assembly and US Congress take effect at the next election – but for the state Senate, the process is staggered, with new district lines taking effect for only half of the districts immediately after redistricting, and the other lines taking effect two years later.