While a Northland cycle network on that scale would take decades to complete, a reported 1000 people a week were already using the Twin Coast Cycle Trail, spawning new businesses such as a railway-themed B&B in Okaihau and Devonshire teas in Horeke, he said.
That influx of visitors opened up other opportunities, including marae stays, and could herald a renaissance for small towns, such as Horeke, which had gone into decline. It also posed a challenge for the council of getting adequate visitor infrastructure set up.
Mr Carter said former Prime Minister John Key was ridiculed at the time for his idea of a national network of cycle ways.
"But look what it has become," he said.
The mayor gave particular thanks to the landowners whose generosity had made the Okaihau-Horeke section possible. Unlike the rest of the trail, there was no rail corridor to follow beyond Okaihau so the trail had to cross private land instead.
People taking part in Saturday's opening could choose between pedalling the full 28km or a 9km loop which included a 1.2km boardwalk through reeds and mangroves beside Hokianga Harbour, one of the trail's most striking features.
More than 100 cyclists of all ages took part, including a couple on scooters and electric bikes and one on a unicycle. The ride was followed by a powhiri at Mangungu Mission Station and a prizegiving. Spot prizes included three mountain bikes.
Those trying out the trail included 1962-66 Commonwealth Games cycling medalist Laurie Byers of Kaikohe. He said the newest section of the trail was "just beautiful" as it descended from Okaihau into the Utakura Valley.
It was a credit to the landowners who had allowed it to happen, Mr Beyers said.
Also taking part in opening were Tai Tokerau MP Kelvin Davis, National's Northland candidate Matt King, and iwi leaders Hirini Tau and Pita Tipene.
The Twin Coast Cycle Trail, or Pou Herenga Tai, started as a Kaikohe-Hokianga Community Board project to open up the old rail corridor between Kaikohe and Okaihau to give locals a safe and enjoyable place to exercise. That section opened in 2011 with Kawakawa to Opua following in 2014.
Construction of the full 84km trail was complicated by Treaty claims, protests, and a funding shortfall which forced the council to go back to the Government cap in hand. It was one of the first out of the starting blocks of the original seven trails in Mr Key's national network but the last to be completed.