They're ponderous, pavement clogging, and capable of disgorging more than 50 visitors at a time; leg-stretching, camera-toting pedestrians who often will swarm en masse onto the boardwalks ringing Yellowstone National Park's geyser basins. And in 2016, those commercial tour buses would have stretched roughly 108 miles if you had parked them end-to-end-to-end.

"Tour bus numbers have grown at kind of exponentially increasing rates. We’ve more than doubled in the last five years," said Ryan Atwell, Yellowstone's resident social scientist.

Whereas 5,411 commercial tour buses, which can stretch 45 feet and seat about 54 passengers, entered the park in 2010, last year the year grew to 12,800, according to Mr. Atwell's numbers.

That's a staggering increase, when you think about tour buses circling Yellowstone's Grand Loop Road, and parking in front of lodges. But that increase in commercial tours does not mean there are fewer lodge rooms in the park for you and me, according to Rick Hoeninghausen, sales and marketing director for Xanterra Parks & Resorts at Yellowstone.

While Mammoth Hotel is closed to guests most of this year due to renovations, all five new lodges at Canyon are available/Xanterra Parks & Resorts

“There are limits by lodge and by location as to where we can put the groups, and how many," he said the other day during a phone call. "That’s been in place for a long time. And by the way, it’s not just lodging, it’s dinner reservations as well."

While some lodging operations in Yellowstone might accept a few more bus tour groups than others, Mr. Hoeninghausen replied when asked how many rooms in the park are reserved for tour bus groups, "it's going to fluctuate a little bit on an annual basis, but in reality, when the dust settles, ir's probably going to fall around 18 percent."

"Some places we have larger amounts. Places like Grant Village, we can put more groups in Grant Village," the official went on. "But at places like Lake Lodge, very few. Old Faithful Lodge. None. Roosevelt Lodge. None."

While it might seem to those who annually search for lodging in Yellowstone that rooms are filling up earlier and earlier each year, Mr. Hoeninghausen couldn't say for sure that that was the case. He did so, however, that construction and renovation projects at the park's lodging bases are affecting how many rooms are available.

“Stuff is out of availability when we’re renovating and building this and that. I haven’t had an apples to apples room inventory for several years now," he said. "Here’s what I can tell you: campground reservations. For the last few years, advance reservations on campgrounds has been tracking higher each year. Which means more people booking earlier. And that usually tells us that A), interest is still strong in Yellowstone, and it's an indicator that lodging will probably track similarly.

"But again, Mammoth (Hotel) is off the books for most of this summer, Canyon (Lodge) is back on. Last year only a couple of Canyon lodges were on to start the year," explained Mr. Hoeninghausen. “Grant Village we’ve been renovating. We’re adding 67 new cabins to Old Faithful Lodge this year that weren’t available last year. Although, they’re not all on (available for booking) yet, because we want to make sure the construction is done on time. That’s the moving target. So, I cannot tell you for sure what’s happening with lodging with any degree of certainty, but when I look at campagrounds, the last few years they’ve been pacing ahead. That tells me that generally people may be in fact booking earlier.”

Concerning Mammoth Hotel, the National Park Service is conducting a multi-phase rehabilitation project that is expected to keep the hotel closed for guests through the coming year. The $7.9 million project, which got underway this past October, will not require closure of the cabins that surround the hotel located near the park's North Entrance near Gardiner, Montana. Inside the hotel, the project is scheduled to include:

• Seismic and structural stabilization of the lobby, Map Room, and Porte Cochere, which will require the construction of shear walls and moment frames. 
• The modernization of the electrical system (including new distribution panels, restoration of historic light fixtures, and upgrades to the emergency lighting system).
• Replace the one-pipe mechanical heating system with a more efficient two-pipe thermostatic controlled system and insulate the heating pipes.
• Upgrade fire-smoke detector systems and fire-sprinkler systems.
• Improve ADA compliance and accessibility.

Against that, Xanterra will have the five new lodges at Canyon up and running this year.

Moran Lodge is one of five new lodges open for guests at Canyon in Yellowstone/Xanterra Parks & Resorts