Wednesday marked  day one of the Honolulu Marathon expo and a milestone for the premier sporting event.

"I don’t think anyone back in 1973 when they had 163 finishers, thought that 40 years  later it would still be going and there would be 32,000 people running it.  It's an amazing phenomenon," said race director Jim Barahal.

Organizers point to the millions of dollars pumped into the economy by non-resident runners.

For a decade, Hawaii Pacific University has been tracking visitor spending by surveying participants.

"There are 17,000 runners from Japan. Each runner is bringing one person with them on average, so there are actually 34,000 coming here for this race," said HPU Professor Jerry Agrusa.

The survey has found that participants are staying longer.

Twenty percent of Japanese visitors plan a neighbor island trip, as well as 60 percent of runners from other places , including  the U.S. mainland, Canada and Australia.

One Tokyo resident who came with friends and plans to stay in Hawaii for ten days, said he is excited just to be in the islands.

"Right now in Japan, it is winter and I run in the cold, so Hawaii is opposite, so I have to adjust," said Daiki Nishiwaki.

And the lingering voggy and humid weather is giving some runners cause for concern.