In an attempt to reduce traffic jams and overcrowding, Muir Woods National Monument will become the first national park unit in the United States to require reservations year-round for all vehicles to enter the park.

Managers of the Marin County preserve, famous for its towering redwood trees, announced Thursday that starting Jan. 16 everybody who plans to bring a car to Muir Woods will need to book a reservation online or by phone. Vehicles without reservations will be turned away at the gate.

The parking lot at Muir Woods has 232 spaces. Reservations will cost $8 per vehicle in addition to the $10 park entrance fee and will be taken starting Jan. 1 at gomuirwoods.com. After that, reservations can be booked 90 days in advance.

“Visitation has continued to increase,” said Darren Brown, a transportation planner with the Golden Gate National Recreation Area, which manages Muir Woods. “The problem is too many cars. It’s extremely crowded, and we can’t handle as many cars that end up going there.”

Last year, 1.1 million people visited Muir Woods, up 30 percent from the decade before. The new reservation system is expected to reduce that number to about 924,000, the National Park Service estimates.

The 554-acre forest, named for naturalist and Sierra Club founder John Muir, was preserved more than a century ago by Marin County Congressman William Kent, who purchased some of the land and donated it to the federal government. President Theodore Roosevelt declared it a national monument in 1908, and Kent went on to become a lead author of the bill that established the National Park Service in 1916.

The property has become wildly popular over the generations, however, receiving up to 6,000 visitors on some summer weekend days. Motorists have parked cars along the winding roads in the area, causing problems and harming the adjacent Redwood Creek, home to endangered coho salmon.

“Some weekends, we’ll have 250 or 300 cars parked down the road more than a mile from the monument,” Brown said. “People were walking in the road. It wasn’t safe.”

The park service will continue to let hikers and bicyclists into Muir Woods without a reservation. Disabled spots will require a reservation like the other parking spaces. The agency plans to post signs starting in January along Highway 101 and other local roads telling people they won’t be allowed into the park without a reservation.

And people who show up at the last minute hoping to make a reservation from the gate will be out of luck. There’s no cellphone service there.

The park service also will expand shuttle bus service, which now runs on summer weekends, to run every weekend beginning Jan. 16. Shuttle reservations are $3.

Environmentalists on Thursday were generally supportive of the overall plan.

“I can certainly count myself among those more than 1 million people who have experienced frustrations when attempting to visit and park my car,” said Kati Schmidt, a spokeswoman for the National Parks Conservation Association in San Francisco. “We support the reservation and shuttle solution.”

Attempts to put similar reservation systems for vehicles in place at other national parks have been met with opposition from local communities, who have worried that it would harm tourism.

Former Yosemite Superintendent B.J. Griffin drew waves of controversy in the mid-1990s when she began exploring the idea as a way to cut down on crowds in that park. She later dropped the idea.

This year, however, with annual visitation now up to 5 million people, Yosemite officials instituted a pilot program for four weekends in August at one parking lot near Yosemite Falls. In February, Haleakala National Park in Hawaii began requiring reservations for anyone wanting to drive a car to the summit of the mountain from 3 a.m. to 7 a.m. to watch the fabled Maui sunrise.

Meanwhile, Zion and Arches national parks in Utah are also studying the idea.

The Muir Woods plan was discussed for several years. At first, the park service proposed building a new remote parking lot along the slopes of Mount Tamalpais, on the Panoramic Highway near Mill Valley. But neighbors vociferously fought that idea — and it was dropped. The park service also proposed building a shuttle bus station near Muir Woods at Muir Beach, but neighbors sued to stop that idea.

The reservation system grew out of a task force of neighbors, business groups, environmentalists and local leaders convened by Rep. Jared Huffman, D-San Rafael.

“There was some controversy when we began discussing it,” Brown said. “Certainly the communities on the approaches to Muir Woods are affected by it. Now everybody is pretty much in agreement.”