Northland retailers earned $599 million in June last year, $566m the year before, and $578m in June 2014.
However, the record June sales are lower than those in the peak tourism season between November and March.
In the December quarter last year, Northland retail sales was $710m and $806m in the March quarter.
Vitalise Whangarei, a group of about 100 retailers committed to putting the vibe back into the city, said any event that brought people and business to town was most welcomed.
Founder Stephanie Mitchell said if Whangarei could attract regular events, people would keep visiting the city.
She said while an unprecedented number of people visited Whangarei during the Lions' tour opener, city leaders should think about how to attract bigger crowds so that benefits were seen more regularly.
Northland Chamber of Commerce chief executive Tony Collins said the region was beginning to prove it could host international sporting fixtures and to cope with an increase in visitor numbers.
"The sporting events in June started the summer season earlier by bringing in more people and money into Northland's economy which is very important.
"The other positive is the investment the region made over a number of years in building capacity to host major events like the Rugby World Cup games, the Fifa U20 matches and even the Fritter Festival are paying dividends," he said.
Mr Collins said even simple investments such as the new Laneway in central Whangarei had made the town a more attractive place for visitors.
"Local businesses like the hospitality and retail sectors are becoming smarter in what they are doing by being open and ready to do business as well as providing really good customer service," he said.
With the growth in hospitality businesses at the Town Basin, improvements to state highways between Northland and Auckland, and the potential benefits to Northland should New Zealand host the next America's Cup, he said the region's tourism industry was tracking in the right direction.
More than 28,000 people attended the World Masters Games in late April, and an estimated 23,000 visitors from the UK and Ireland came for the Lions' tour.