The "Census Act 1877" required censuses to be held every fifth year and is well embedded in legislation and government systems. Since 1881, censuses have been held every five years, with the exceptions of those in 1931 and 1941 and the one in 2011 which was cancelled due to the February 2011 earthquake in Christchurch, which displaced many Canterbury residents from their homes only a few weeks before census day. It was rescheduled for March 2013, so the 2013 census is the previous census completed before this one.