Banff accommodations were nearly fully booked this summer as visitor numbers surged again, prompting Parks Canada to advise people planning trips for 2017 — when admission will be free — to book early and consider less popular times and places to visit.

"We know that accommodations are pretty much at their max now," said Greg Danchuk, visitor experience manager for the Banff field unit.

"We've already seen a good increase in [visitation]. How much more is possible, we don't know. We'll have to see that. But we're preparing."

Banff National Park attracted 1.573 million visitors between April and July this year. That's an increase of 4.9 per cent from the year before and 25.5 per cent compared with 2011.

Kootenay, Yoho and Jasper national parks had similar increases.

Click on this interactive graph to see visitation numbers in each national park:

Danchuk said a combination of factors is likely behind this year's growth in visitation, including the relatively low Canadian dollar, effective tourism marketing and the low price of gas.

Parks Canada doesn't yet have detailed data on where this summer's visitors came from, but Danchuk said staff have observed more Americans, in particular, than in the past.

Cars line up outside the east gate to Banff National Park. (CBC)

Waterton Lakes National Park, which runs along the U.S. border in southwestern Alberta, saw a 12.5 per cent increase in total visitation from April to July this year compared to last, but a large part of that was due to construction traffic entering the park.

Factoring out the construction vehicles, the increase in regular visitor traffic was closer to eight per cent, said John Stoesser with the Wateron Lakes field unit.

Alberta Tourism Minister Ricardo Miranda said the occupancy rate in the communities of Banff, Lake Louise, Kananaskis, Canmore and Jasper jumped to 93.1 per cent in July.

"This is the highest rate since 2005, when Alberta Culture and Tourism began tracking occupancy in these resort communities," he said in a release.

Preparing for 2017

Danchuk said iconic sites like Lake Louise will continue to have shuttle buses running from an overflow parking lot to handle all the demand during peak season, but there's only so much space.

"We try to tell people about some of the lesser visited locations within the park, to try to spread people around," he said.

"Not everybody wants to see just the icons. They'll venture a little farther and there's a lot of very accessible, shorter hikes and vistas to see that people might not be aware of."

In addition to the busy summer season, crowds often descend on Lake Louise in mid-to-late-September to get a glimpse of the fleeting, golden fall colours. (CBC)

People looking to camp should know that the reservation system will open again in January 2017, Danchuk noted.

Reservations for a given year used to open in April, but Parks Canada bumped that up to January this year and plans to continue with that schedule.

"We highly, highly recommend that people use the reservation system," Danchuk said.

"If you want to camp, book ahead. Plan your visit. It will be a much better experience."