Following a record-breaking year for leisure travel in 2016, vacation spending in 2017 will be flat.

The 2017 Portrait of American Travelers study, now in its 27th year, measures more than 2,000 variables and is based on 3,000 U.S. adult responses who took at least one overnight trip, a minimum of 75 miles from home, last year. According to the survey, the United States estimated 60 million traveling households will spend up to 5 billion less on leisure travel this year.

While travelers reported spending an average $4,833 on vacations throughout the last 12 months — the second-highest amount in eight years — it represents a 4 percent drop from 2016. Travelers said they planned to spend an average $4,815 on vacations in the next year, less than the previous year. This means of the 60 million traveling households, up to $9.2 billion less will be spent on leisure travel.

Millennials now account for the largest generational population in the United States and is the only generation to report spending more on future travel. Millennial families make up about 16 percent of American travelers, and took a combined 36.9 million vacations, spending $50.4 billion on leisure travel in the last 12 months.

While U.S. travelers only intend to travel 6 percent more this year, millennial families plan to travel 35 percent more, spending 38 percent more than millennial couples on vacation and 88 percent more than millennial singles. About 26 percent of millennial families vacation in international destinations, compared to less than 20 percent of millennial couples or singles.