Large vehicles will no longer be allowed to drive across Utah’s Zion National Park starting June 7. With tour buses, RVs and trailers over the size limits prohibited from traversing the Zion-Mt. Carmel Highway, park staff want to make sure visitors plan to avoid a roadblock in their travel plans.
The highway is the main road between the park’s east entrance and the mouth of Zion Canyon. It features more than a dozen sharp curves, narrow lanes and steep drop-offs, in addition to historic tunnels and bridges. Zion transportation manager Lisa White said the change is meant to improve traffic and safety.
“I don't care how good of a driver you are, if your vehicle physically does not fit on the roadway, you're not going to stay in your own lane,” she said.
The rule will make the road off-limits to vehicles longer than 35 feet 9 inches, taller than 11 feet 4 inches, wider than 7 feet 10 inches or with a weight over 50,000 pounds. For trucks towing trailers, the length limit is a combined total of 50 feet.
The two-lane highway was completed in 1930, when the average car or truck was smaller and lighter than modern vehicles. The park’s crowds have changed this century, too. Now the nation’s second-most popular national park, Zion’s visitation has increased around 90-fold since 1930.
“For the most part, the response that we've gotten is either ‘Hallelujah, thank you,’ or ‘We don't like it, but we understand,” White said.
The Zion-Mt. Carmel Tunnel doesn’t allow clearance for two large vehicles at the same time, so park staff currently need to stop traffic to escort them one at a time. A 2016 study found that it results in an average of 41 minutes of blocked traffic each hour along the highway.
Widening the road or tunnel to accommodate bigger vehicles wouldn’t make sense, said park spokesperson Matthew Fink.
“In addition to the fact that it's not practical, also the majority of the highway is adjacent to wilderness areas, so it's protected anyway,” he said.
Zion announced the new rule without its start date back in 2024, but as the busy summer season looms, officials are still trying to make sure future visitors get the message.
The park is particularly trying to reach people who drive vehicles that are just barely over the size limits and may not realize the rule applies to them. One such example is people who own a dually truck, a type of heavy-duty pickup that’s extra wide because it has four wheels on the rear axle.
The change will also impact tour companies that often carry visitors into Zion by the busload.
Shawn Horman is director of group sales with Southwest Adventure Tours, a Cedar City company that runs charter buses through Zion. They’ve already adjusted to offer a smaller shuttle option for customers who still want to experience the park by road and are booking it.
“Our biggest issue may be: Do we have enough vehicles to handle the volume?” he said. “So yeah, we're seeing a positive response.”
A visitor on a large bus tour could hop off at specific spots east or west of the highway and ride through the park on a guided shuttle service while the bus drives around to meet them on the other side. But that would need to be chartered ahead of time and will add an extra cost, Horman said, which some of the tour companies his team works with may not have planned for.
Communication from the park has been pretty good, Horman said, but it would have been better if tour companies had more advance notice of the exact date the rule takes effect. Many bus operators book trips 18 months ahead, he said, so it’s been tricky to offer some routes for the spring and others for the summer.
“To have something that starts mid-year is so difficult,” he said. “So, it threw a lot of companies off.”
Large vehicles will still be permitted to go through Zion’s south entrance and park at the main visitor center. They will also be able to drive to Zion Lodge with a reservation or to stay at one of the park’s campgrounds.
From the visitor center, tourists could access Zion Canyon aboard the park’s free electric shuttle service. But those shuttles don’t go through the historic tunnel or to popular east side stops such as Checkerboard Mesa or the Canyon Overlook Trail.
Park partners hope to launch a shuttle that might cover some of that ground in future years, after the Zion Discovery Center opens at the park’s east entrance. But none of that will be up and running this summer.
The park plans to enforce the size limits at the entrance gates, where rangers will measure vehicle dimensions and educate drivers about where they can and can’t go. During the transition period this year, White said it may also post some rangers at Canyon Junction, the spot on the highway where the restriction begins.
“We can't promise it's going to be a 24/7 because, as we've talked about a lot, the Park Service has limitations on our staff,” White said. “But we will be trying to have someone there whenever possible to be that second line of defense to turn people around.”
Zion remains generally understaffed relative to its exploding visitation numbers. More staff reductions have come to parks nationwide from federal firings, buyouts and hiring freezes introduced by President Donald Trump in 2025.
