The Transport Agency says there were extensive delays on Friday for motorists leaving Auckland and Wellington.
It says people heading north to Warkworth, or south to Waikato and State Highways 2 and 26, faced delays of an hour or more.
A serious crash on State Highway 25 between Tairua and Whitianga, also delayed traffic.
The police say speed appeared to be a factor in that single-vehicle Coromandel crash, which injured six people, two of them seriously.
Just before1pm, the van failed to negotiate a tight, 25-kilometre an hour corner and went down a 20-metre bank.
A two-year-old child and a woman were flown to hospital with serious injuries and four others had been treated for less severe injuries.
Motorists heading up the Kapiti Coast north of Wellington also faced delays of more than an hour.
The police reported congestion on other parts of State Highway One as far north as Waiouru.
They say patience was necessary and people were warned to either leave earlier than planned for their destination, or delay their travel if possible.
