With Labor Day marking the unofficial end to the travel season, the hotel industry is coming off its strongest three months of demand since at least 1987, said Jan Freitag, a senior vice president at STR Inc.

From May through July, about 322 million room nights were sold, the most since the Tennessee-based research company began tracking the figures. August data are scheduled for release Sept. 18, and preliminary information suggests another record month, he said.

“Summer travel has been very healthy,” boosting year-to-date demand, which is up more than 4 percent from the first seven months of 2013, Freitag said. This increase is driven by a confluence of increased bookings by business, group and leisure travelers from the U.S. and abroad, he said.

About 34.7 million Americans took trips of 50 miles or more from their homes during the recent holiday weekend, the most since 2008, according to a forecast from AAA. based in Heathrow, That would be a 1.3 percent increase from 2013 and follows projected gains of 1.9 percent for the Fourth of July and 1.5 percent for Memorial Day holiday weekends, data from the largest U.S. motoring organization show.

Save 75% on a Digital Subscription Today

One indication of the “healthy return of leisure travel” is reservations for Saturday nights, at almost 83 percent occupancy in July, Freitag said. “This speaks to very strong demand on weekends.”

Consumer travel makes up about 30 percent of total U.S. hotel bookings, and while there’s “still a little bit of the have and have not” among American consumers, economic growth in some countries outside the U.S. has been a “tremendous benefit” to the industry, said Bill Crow, an analyst in St. Petersburg, Florida, at Raymond James & Associates.

Recent gains have been buoyed in part by group travel — including conventions, weddings and other blocks of four or more rooms — which had been slow to rebound as the industry recovered from the recession, Hach said. That’s because many companies faced public scrutiny for throwing lavish corporate events and consumers cut back on personal travel, he added.