The 1941 New Zealand census had been postponed due to World War II, so the 1946 electoral redistribution had to take ten years of population growth and movements into account.
[5] After years of political tension, the National Government came to an agreement with the Labour Party on the redistribution provisions of the electoral law.
Combined with significant population redistributions within the islands, the boundaries of all but two electorates were altered.
[7] The electorate included the population centres of Matamata, Cambridge, Morrinsville, Te Aroha, Waharoa, Waitoa, Huntly, Ngāruawāhia, and Ohaupo.
Under boundary changes for the 2008 election, Piako ceased to exist as an electorate.