US Travel Association president and chief executive Roger Dow called it the "IPW effect".
"The brand exposure the city gets as a result of the show creates an additional one million visitors for the city," Dow said in Chicago. "It delivers more to the city than the Super Bowl by many times. In fact, IPW keeps giving and giving for years to come."
Dow saluted the recent rise of the federal Government's Brand USA in focusing and spreading US tourism's message globally.
"It's evidence that the US Government is beginning to understand what so many countries have understood for decades," he said. "Brand USA has done some terrific things."
The Obama Government gave Brand USA the task of achieving 100 million international visitors a year by 2021, up 61 per cent from 62 million in 2011. Dow conceded the numbers should be easily reached. To meet the President's target, the USA needed to add 6.2 million visitors a year; it actually added 7.1 million.
The first wave of Brand USA's marketing saw them move into big regions, like Britain, Canada and Japan. They've come to New Zealand in the second wave. On these shores, Brand USA has partnered with APN, owners of the Herald, and with Let's Travel magazine.
New Zealand representative Wayne Mitchum said 209,000 New Zealanders visited the US last year, a 12.6 per cent increase on the previous year. The strength of the New Zealand dollar and increased air capacity had helped drive that growth.
It's big business. At last month's closing night function, Oscar and Grammy winner Jennifer Hudson sang at an exclusive event inside Chicago's Museum of Industry and Technology - which has a U-boat in the basement. Now that's a big party.
• Winston Aldworth travelled to Chicago courtesy of IPW and Air New Zealand.