Project-based business travel spending reached $45.4 billion in the US in 2017, making up 15 percent of the total in that category, according to a study from the Global Business Travel Association in partnership with InterContinental Hotels Group. In all, 66 million trips were taken last year for project-based purposes, representing 12 percent of all US business trips and 19 percent of all US business trips taken for transient purposes. To be considered project-based travel, according to the report, a trip must revolve around a project, have both a start and an end date and have a duration of at least four nights or have some recurring component. It does not include group travel, relocation or travel for training. Michael W. McCormick, GBTA executive director, said that demand for project-based business travel will continue to rise, with top project-intense sectors forecast to grow faster than the broader economy in the coming years.