This Monday is Veterans Day.

It also marks a free entrance day at national parks across the United States, the last one for this year.

Chuck Sams, the National Park Service Director and Navy veteran, expressed enthusiasm for the public to experience national parks on Veterans Day. He specifically encourages active duty military, veterans, their dependents, and Gold Star Families to obtain a Military Pass for free admission to parks any day. “As a veteran, I love seeing fellow veterans and their families enjoying our national parks, diving into our country’s history, and finding tranquility in nature,” he said.

Here’s what park enthusiasts should keep in mind.

Are all national parks in the US free?

On free-entrance days, there is no charge to enter national parks, and there are six such days this year.

Throughout the rest of the year, about 25% of the parks in the National Park System do require entry fees, including many of the most visited ones. These fees usually cover access for multiple days and for all occupants of a single vehicle.

Travelers can find out which parks charge fees by visiting the National Park Service’s website or specific park pages.

Veterans, service members, their dependents, Gold Star families, fourth graders with their families, and U.S. citizens or permanent residents with permanent disabilities can enjoy free access to national parks throughout the year.

Is there a national park in every state?

The National Park System consists of 431 units that include various types of parks, such as battlefields, historical sites, parkways, and seashores. According to this broad categorization, every state has a national park.

However, only 63 of these sites are what many conventionally regard as national parks, such as Yellowstone and the Grand Canyon. Not every state is home to one of these more widely recognized parks. Some states, for instance, Utah and California, feature several national parks, many of which do have entrance fees.

Visitors can discover the closest national park by checking the National Park Service’s Find a Park webpage.

Why do national parks charge admission fees?

The income from these fees is plowed back into enhancing facilities for visitors, including improving accessibility at Acadia National Park, refurbishing boardwalks at Everglades National Park, and restoring the Many Glacier Hotel at Glacier National Park.

According to the National Park Service, “at least 80% of revenue generated from entrance fees is retained in the park where it’s collected, while the remaining 20% supports parks that either do not collect fees or generate limited revenue.” The service provides specific examples of how fee proceeds are allocated through an interactive map on its website.