Rakaia is a town sited on the southern banks of the Rakaia River on the Canterbury Plains in New Zealand's South Island, approximately 57 km south of Christchurch on State Highway 1 and the Main South Line. Immediately north of the township are New Zealand's longest road bridge and longest rail bridge, both of which cross the wide shingle beds of the braided river at this point. Both bridges are approximately 1,750 metres (5,740 ft) in length.

State Highway 1 is the longest and most significant road in the New Zealand road network, running the length of both main islands. It appears on road maps as SH 1 and on road signs as a white number 1 on a red shield, but it has the official designations SH 1N in the North Island, SH 1S in the South Island.