(CNN) — Nearly 331 million people visited the National Park Service's 417 sites around the United States in 2017, a slight dip from the 331 million record-breaking visits during its centennial anniversary year in 2016.

Park service officials expected the slight decline after the centennial celebrations during the previous year. In 2016, the park service recorded its third consecutive all-time attendance record, and 77 national park sites set new records for annual recreation visits. (Of the 417 sites in the National Park Service, 385 count visits.)

While attendance numbers remained relatively stable, people actually spent more time in the parks in 2017 -- more than 1.4 billion hours last year, an increase of 19 million hours over 2016.

"Our National Parks are being loved to death," said US Interior Secretary Ryan Zinke in a statement, whose agency oversees the National Park Service.

"As visitor rates continue at a high level, we must prioritize much-needed deferred maintenance including aging facilities, roads and other critical infrastructure. President Trump's proposal to establish a Public Lands Infrastructure Fund is a step in the right direction. This is not a Republican or Democrat issue, this is an American issue, and the President and I remain ready to work with anyone in Congress who is willing to get the job done."

Zinke was referring to the $11.6 billion in deferred maintenance at the nation's 417 National Park Service sites, which include the 59 headliner National Parks as well as national recreation areas, seashores, parkways, memorials, battlefields and more. Increased attendance at the destinations , only 118 of which charge admission, means that many locations can't keep up with repairs.

To make the point, the National Park Service released cost estimates for deferred maintenance at each of the top 10 most popular park sites and national parks.

Top three parks attract more than 40 million visits

Great Smoky Mountains National Park National Park Service

The Blue Ridge Parkway (16 million visitors) took back the number one slot from 2016 winner Golden Gate National Recreation Area, which came in second place with nearly 15 million visitors last year.

Great Smoky Mountains National Park (11.4 million) came in third place, followed by Gateway National Recreation Area (9.2 million) and the Lincoln Memorial (nearly 8 million).

The top 10 park sites attracted more than 5 million recreation visits each, including Lake Mead National Recreation Area, George Washington Memorial Parkway, Natchez Trace Parkway, Grand Canyon National Park and the Vietnam Veterans Memorial.

Trump's first year in office

Bears Ears National Monument George Frey/Getty Images North America/Getty Images

President Barack Obama created more than a dozen National Park Service monuments during his eight years in office, including four in his final days. Some of those sites honored the country's civil rights struggle, African-American history, Japanese-American history and the fight for women's rights

after declaring that he would reduce the size of two Bureau of Land Management monuments in Utah. (Like the National Park Service, the Bureau of Land Management is within the Department of the Interior.) What's attracted a lot of attention doesn't involve the National Park Service at all. Trump signed two presidential proclamations on December 4 after declaring that he would reduce the size of two Bureau of Land Management monuments in Utah.(Like the National Park Service, the Bureau of Land Management is within the Department of the Interior.)

The two presidential proclamations split Bears Ears into two national monuments and Grand Staircase-Escalante into three separate monuments.

In response, a group of Native American tribes filed a lawsuit against Trump and several administration officials claiming that his decision to shrink the Bears Ears National Monument significantly is "in violation of the United States Constitution and the Antiquities Act of 1906."

Separately, US conservation organizations sued Trump and Zinke for actions regarding the Grand Staircase-Escalante National Monument. (Obama created Bears Ears, and President Bill Clinton created Grand Staircase-Escalante.)

Most popular National Park Service sites (417 total)

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1. Blue Ridge Parkway (NC/VA): 16,093,765 visits ($461,564,707 million deferred maintenance)

2. Golden Gate National Recreation Area (CA): 14,981,897 visits ($325,814,011 deferred maintenance)

3. Great Smoky Mountains National Park (NC/TN): 11,388,893 visits ($215,451,902 deferred maintenance)

4. Gateway National Recreation Area (NY/NJ): 9,190,610 visits ($788,419,471 deferred maintenance)

5. Lincoln Memorial (DC): 7,956,117 visits ($33,868,238 deferred maintenance)

6. Lake Mead National Recreation Area (AZ/NV): 7,882,339 visits ($205,540,564 deferred maintenance)

7. George Washington Memorial Parkway (DC/MD/VA): 7,562,793 visits ($655,330,330 deferred maintenance)

8. Natchez Trace Parkway (AL/MS/TN): 6,326,062 visits ($361,294,324 deferred maintenance)

9. Grand Canyon National Park (AZ): 6,254,238 visits ($329,437,056 deferred maintenance)

10. Vietnam Veterans Memorial (DC): 5,072,589 visits ($625,250 deferred maintenance)

Most popular National Parks (59 total)

l e v a r t

1. Great Smoky Mountains National Park (NC/TN): 11,388,893 visits ($215,451,902 deferred maintenance)

2. Grand Canyon National Park (AZ): 6,254,238 visits ($329,437,056 deferred maintenance)

3. Zion National Park (UT): 4,504,812 visits ($65,291,893 deferred maintenance)

4. Rocky Mountain National Park (CO): 4,437,215 visits ($84,234,245 deferred maintenance)

5. Yosemite National Park (CA): 4,336,890 visits ($582,670,827 deferred maintenance)

6. Yellowstone National Park (ID/MT/WY): 4,116,524 visits ($515,808,008 deferred maintenance)

7. Acadia National Park (ME): 3,509,271 visits ($59,858,099 deferred maintenance)

8. Olympic National Park (WA): 3,401,996 visits ($120,719,515 deferred maintenance)

9. Grand Teton National Park (WY): 3,317,000 visits ($178,630,525 deferred maintenance)

10, Glacier National Park (MT): 3,305,512 visits ($153,838,276 deferred maintenance)

Free for fourth-graders

Every fourth-grader around the country can still get a free one-year national parks pass for the student and his or her family under the "Every Kid in a Park" program, which has attracted more than 350,000 fourth-graders in its first two years of operation.