The deepest lake in the U.S. has hit historic highs, smashing its old records for annual visitation during 2016.

A total 756,344 people visited Crater Lake National Park last year, according to figures provided by the National Park Service, 23 percent more than the number of visitors who came through in 2015.

That number is by far the biggest the park has ever seen, and is the biggest annual increase in recreational visits since 1976. It's also the seventh straight year of growth for Crater Lake, a positive trend dating back to 2009.

That trend is part of a nationwide upswing for national parks, which have been attracting visitors at a rapid pace over the last few years.

"National parks just caught the public's attention," National Park Service spokesman Jeff Olson said. "People became interested in national parks and the [2016] centennial. We had lots of help."

Last year the National Park Service celebrated its 100th anniversary with special events, a documentary and plenty of press. That event, combined with newer programs like fee-free days and Every Kid in a Park, may have helped buoy visitation numbers to new highs - especially at Crater Lake.

In addition to the recreational visits, there was a dramatic increase in the number of backcountry overnight stays in 2016, with 4,706 people camping out in the wild compared to 3,253 in 2015. Stays at Crater Lake Lodge and the Mazama Cabins also increased slightly, though visitation to the park's two campgrounds dipped.

The year started off slow for Crater Lake, which saw a decrease in visitation every month across winter and spring. But people flocked to the park come summer, the crowds peaking in July and August, when visitation numbers topped 2015 counts by 19 and 33 percent, respectively.

Year-end numbers aren't yet available for the rest of the Pacific Northwest's national parks, but early indications show positive trends all around.

Mount Rainier National Park saw a 9 percent increase in 2016, bringing in 1.2 million people through November, while Olympic National Park also saw a solid growth in recreational visits, hosting 3.3 million people through November - a 3.8 percent increase. North Cascades National Park hosted more than 28,000 people last year, marking the first time since 1998 that it's crossed that threshold.

Oregon's smaller national park sites also did well, according to numbers reported this fall. The John Day Fossil Beds saw a 5.3 percent increase in recreational visits as of October's visitation report, while the Oregon Caves saw an 8.6 percent increase through November.

The Fort Vancouver National Historic Site, meanwhile, might well have eclipsed 1 million visitors in 2016. The national park site was already at 965,912 annual visits, according to an October report - a whopping 29.4 percent increase over 2015. The park has reached the million milestone only once before, in 2009.

No matter what the reason for the crwods, park officials see the increased visitation as a big win for national parks. At Crater Lake and sites around the Pacific Northwest, it could mean a new generation of people with interest in public lands.

"It teaches them about national parks, lets them discover the value for themselves and it helps us start that stewardships conversation with younger people," Olson said.

--Jamie Hale | jhale@oregonian.com | @HaleJamesB