State Highway 21 (New Zealand)
State Highway 21 (SH 21) is a short 6.7 km stretch of road in the North Island of New Zealand. It links State Highway 1 (Waikato Expressway) at Tamahere with State Highway 3 at Ōhaupō. The highway’s main destinations are Hamilton Airport and Mystery Creek, where the National Agricultural Fieldays are held.
SH 21 was designated as a state highway in 1997. Its number is unusually far south of the normal NZ pattern for highway numbers, so it sits well south of where most SH 2x routes are found (the second-southern SH 2x after SH 28).
At the Hamilton Airport exit, signs once showed Hamilton in both directions. In 2015 the signs were updated so the left route goes to Hamilton, and the right route is labeled "Hamilton via State Highway 3" to reduce confusion.
The Narrows Bridge near Tamahere has a long history. The original bridge opened in 1879 and was blown up in 1940. The current bridge opened around 1939–40 and features a 49.5 m reinforced concrete span with a 31 m steel arch. It is located about 1.78 km from the Tamahere end of SH 21, is 20 ft wide with a 5 ft footpath, and is listed as a NZ Historic Places Category 2 site (since 1985). The river banks were reinforced in 2010 to protect the foundations. Traffic on the bridge has varied from about 4,900 to 5,600 vehicles per day between 2008 and 2015.
This page was last edited on 2 February 2026, at 16:48 (CET).