Amid all the hoopla, celebration, and excitement surrounding the National Park Service's 100th birthday this year, one fact is inescapable: Lodging in the parks this summer will be hard to find. But...it won't be impossible to find.

There are thousands of rooms throughout the National Park System, and if you toss in all the gateway communities and their lodging possibilities, well, you'd be hard-pressed not to find a room in, or near, a national park if you really put your mind to it. Will it be below Yosemite Falls, or facing Old Faithful? Probably not, for those rooms surely were reserved months ago. 

But if you're patient, and flexible, a room is waiting in the park system for you.

“Depending upon the park, and the location, depending on the flexibility of our guests, there are still some great opportunities to book," said Sandy Heilman, vice president of sales and marketing, Aramark, Leisure Division. "Certainly, I would suggest based on what everyone is forecasting at this point is that people start to think about it if there’s something they want to do this summer. At this point, May and June, we still see some opportunity, but they’re pacing farther ahead for early summer, late spring, than we’ve seen in the past."

More than 307 million visitors explored the National Park System last year, a record turnout, and this year the number is expected to go even higher. Many of those visits will be to parks that see a lot of day traffic, places such as Muir Woods National Monument north of San Francisco, Rocky Mountain National Park north of Denver, Great Smoky Mountains National Park that straddles the Tennessee-North Carolina border, the collection of destinations within Boston Harbor Islands National Recreation Area in Massachusetts, and far-flung units such as Fort Laramie National Historic Site in Wyoming and Fort Union Trading Post National National Historic Site in western North Dakota.

But a fair amount will be heading for a night or more in Yellowstone National Park in Wyoming, Yosemite National Park in California, Grand Canyon National Park in Arizona, and Shenandoah National Park in Virginia. And most of those folks, very possibly aware that 2016 would mark the centennial of the National Park Service, made their reservation last year. 

Still, not all is lost.

Get adventurous and rent a houseboat on Lake Powell this summer, or visit Defiance Lodge at Bullfrog in Glen Canyon National Recreation Area/Aramark

"There are cancellations all the time," replied Darla Cook, vice president, public relations, for Forever Resorts, when asked how hard it would be this summer to land a room at one of their lodges in Grand Canyon National Park, Grand Teton National Park, Big Bend National Park, Mammoth Cave National Park, Badlands National Park, Isle Royale National Park, Bryce Canyon National Park, or Lake Mead National Recreation Area. 

If you decide at the last minute to visit a national park this summer and want to try the cancellation route and you're flexible, she said, start calling the lodging desk about two weeks out from your desired time of travel to inquire about sudden vacancies.

But if you're hoping for that room overlooking Yellowstone Lake or the Old Faithful geyser basin, well, that might be hoping for too much.

"In our particular parks, because they’re among the most iconic and well known, globally, we always sell out in the summer. Always," said Betsy O'Rourke, sales and marketing director for Xanterra Parks & Resorts, which long has run the lodges in Yellowstone and also has properties at Grand Canyon National Park, Crater Lake National Park, Death Valley National Park, Glacier National Park, and Zion National Park. "And for our seasonal operations, we sell out from the day we open to the day we close."

Still, more and more travelers are learning that the summer months are not the best for visiting the national parks, and the crowds are only one reason. Look to the shoulder seasons, both before and after the summer months, and you could find cooler weather, fewer crowds and insects, better wildlife viewing opportunities, and more rooms.

"What I always say," Ms. O'Rourke went on, "is if you’re willing to go on the shoulders or in the winter, then Grand Canyon, Yellowstone, and Zion, we can often accommodate. Maybe not on weekends, but certainly during the week.”

If you're set on the summer months, look north, to Alaska, where Aramark has lodges in Denali National Park and Preserve.

"We still have some availability up at Denali Park Village, the early parts of the week," said Ms. Heilman. "Obviously, we do a great deal of contract business with the cruise companies and the land tours that come in. But there’s certainly opportunity We’ve expanded up there, we’re opening some additional rooms at Denali Park Village this year, which will hopefully help get more people up to experience that."

And if that's too far to travel, another good strategy for landing a room is to consider parks that others might not. Aramark has hundreds of rooms at Lake Powell in Glen Canyon National Recreation Area in Utah and Arizona. Look to the Defiance Lodge at Bullfrog, which is even more remote than the Lake Powell Resort, and your odds might go up.

“The lake is just as awesome" at Bullfrog, said Ms. Heilman. ” We’re seeing it tighten up just a bit in terms of that booking window, but we’re kicking off a lot of promotions as well.”

Delaware North's properties invite you to get off the usual path to park lodgings. You wouldn't think Shenandoah National Park, less than two hours from Washington, D.C., to have summer vacancies, but it does, notes Andy Grinsfelder, the company's vice president of marketing .

Shenandoah National Park, although less than two hours from Washington, D.C., does not completely sell out Big Meadows Lodge every day of the summer/NPS

Shenandoah "is one that is often overlooked," he said. "You can find openings throughout the summer at Big Meadows Lodge or Skyland, or even Lewis Mountain, the cabins at Lewis Mountain. And from a summer perspective, they offer so much to do there. They really do keep it engaging. Most evenings they have live performances, like clogging. I’ve never seen clogging until I went there. Music. They try to keep it lively. They have night sky programs."

There also are special culinary affairs at Shenandoah, wine pairings, whiskey pairings, and a blackberry festival come July, said Mr. Grinsfelder.

"Some of the rooms will fill up, some of the cabins," he replied when I expressed surprise about being able to land a reservation in mid-summer, "(but) because there’s such a myriad of room types there, there’s always something available.  I wouldn’t say wait to the last minute, but it’s one of the easier (parks) to find accommodations.”

Also in Delaware North's parks portfolio are Peaks of Otter Lodge along the Blue Ridge Parkway and hotel properties in West Yellowstone just outside Yellowstone National Park, in Whitefish, Montana, not too far from Glacier National Park, and at Fish Camp, California, not far from Yosemite National Park.

“We did some renovations this year at Peaks of Otter," pointed out Mr. Grinsfelder. "We added some color to the place and upgraded the rooms. Fresh coat of paint in the main building. Those who have been going for years will notice the difference pretty easily.”

Stay at Peaks of Otter and you have mountains to hike through, tubing and kayaking on the James River, and even nighttime astronomy programs.

If you're really thinking of changing things up, go abroad. Xanterra owns both Country Walkers, which leads hiking treks in Europe and Canada that touch national parks, and their Windstar Cruises line visits several national parks in Costa Rica and Panama.

"It’s basically getting away from the maddening crowd, if you will. One of the beautiful things about Windstar Cruises is they go to, as we like to say, hidden harbors and small ports. So you can find these little gems," Ms. O'Rourke said. "Same thing with (Vermont Bicycle Tours) and Country Walkers. They’re taking their guests into those areas that are far less developed, far less tracked by tourists, and much more local. So they might be well known to locals, but not well known to international visitors.”

But if a visit somewhere in the world's greatest national park system, the one right here in the United States, is what you're really hoping for this summer, don't despair.

"I think there are within the entire portfolio of the National Park Service, every location is so unique, just an amazing adventure on its own," Aramark's Ms. Heilman said. "I think the opportunities abound, depending on the type of experience that you’re looking for.

“I think there are a lot of smaller parks across the country that, quite honestly, are hidden gems.”

Finally, what would a travel story be without a little secret takeaway?

"Historically, the week before Labor Day weekend tends to be a 'soft week' for travel and availability in a number of our park operations, including the North Rim, as well as our other travel destinations in the USA," said Forever Resorts' Ms. Cook. "That's at least what I've seen during the 34 years I've been in the travel industry."

A less-known-park lodge, such as Peaks of Otter Lodge along the Blue Ridge Parkway, doesn't mean a lesser national park experience/David and Kay Scott