The Trump administration is considering substantial increases in entrance fees to 17 of the most popular national parks across the country during the peak summer season, asking Americans to pay prices that rival the gate costs of amusement parks such as Six Flags and Busch Gardens.

Starting as early as Jan. 2, the entrance fee for a single automobile would spike to $70 at one park — the largest price increase since World War II.

A similar increase at 12 more parks would take effect in May and then at the final four in June.

The cost of riding a motorcycle into the parks would rise to $50 and walking or biking in would cost $30.

In a statement, the National Park Service said the fee increases would raise $70 million more toward addressing an $11 billion backlog in park maintenance to repair deteriorating buildings, restrooms and roads.

“The infrastructure of our national parks is aging and in need of renovation and restoration,” Interior Secretary Ryan Zinke said in a statement announcing the decision on Wednesday. “Targeted fee increases at some of our most-visited parks will help ensure that they are protected and preserved in perpetuity and that visitors enjoy a world-class experience that mirrors the amazing destinations they are visiting.”

The statement does not mention the president’s 2018 budget proposal to cut nearly $400 million from the parks. Nor does it mention bipartisan bills in Congress that would divert $12 billion in federal oil and gas royalties from the national treasury to fund the parks’ maintenance backlog over 30 years.

Zinke and the Trump administration have yet to publicly support or oppose the bills, known collectively as the National Park Service Legacy Act.

The statement notes that entrance fees are charged at 118 of the Park Service’s 417 sites.

Some of the parks affected under the proposal include Shenandoah in Virginia, Acadia in Maine, Grand Canyon in Arizona, Joshua Tree and Yosemite in California, Olympic in Washington, Glacier in Montana, Zion in Utah and Yellowstone in Wyoming, Montana and Idaho.

A 30-day comment period will run until Thanksgiving.

In 2015, the Park Service’s plan to implement fee increases of about $15 per vehicle allowed for a seven-month comment period and meetings near the affected parks, according to the National Parks Conservation Association.

“The president is proposing these huge cuts in the budget, then turning and asking people to pay these exorbitant fees to fund the maintenance needs in our parks,” Emily Douce, the association’s director of budget and appropriations, said on Thursday. “Congress helped establish many of the national parks for the American people, and it’s up to Congress to pay for the backlog. Fees are necessary, but they need to be affordable.”

However, Will Shafroth, president and chief executive of the National Park Foundation, suggested that the price increases were reasonable for most Americans.

“They’re trying to do something tangible,” Shafroth said. At the very least, “it’s provocative in the way that it’s going to get people thinking about this.”