(NEXSTAR) - For one day only in August, you can get into any of our national parks for free.

There are seven such days throughout the year in which free admission is offered to everyone at National Park Service sites that typically charge an entrance fee. This year, those dates include January 9, which was a National Day of Mourning for President Jimmy Carter; Martin Luther King, Jr. Day on January 20; April 19, to commemorate National Park Week; and June 19 for Juneteenth.

Monday, August 4, marks five years since President Donald Trump signed the Great American Outdoors Act. Ever since, parks that otherwise charge entrance fees have waived their cover charge. Fees are still required for overnight camping, cabin rentals, transportation, group day use, and use of special areas.

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After Monday, the next scheduled free entrance days are September 27, for National Public Lands Day, and Veterans Day, on November 11.

Which national parks charge entrance fees?

Of the 475 sites within NPS's purview, 106 require an entrance pass.

In some cases, the fee applies only at certain times. For example, between early June and the end of October, there is no per-person cost to get into Adams National Historical Park. Others may charge only by vehicle rather than per-person fees.

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Below are the national parks that would otherwise charge you to get in, but won't be on Monday, according to NPS.

Acadia National ParkDeath Valley National ParkHovenweep National MonumentRocky Mountain National ParkAntietam National BattlefieldDenali National Park & PreserveIndiana Dunes National ParkSaguaro National ParkArches National ParkDevils Tower National MonumentIsle Royale National ParkSaint-Gaudens National Historical ParkAssateague Island National SeashoreDinosaur National MonumentJoshua Tree National ParkSan Juan National Historic SiteBandelier National MonumentDry Tortugas National ParkKennesaw Mountain National Battlefield ParkSequoia & Kings Canyon National ParksBig Bend National ParkEverglades National ParkLake Mead National Recreation AreaShenandoah National ParkBlack Canyon of The Gunnison National ParkFlorissant Fossil Beds National MonumentLassen Volcanic National ParkSleeping Bear Dunes National LakeshoreBryce Canyon National ParkFort Davis National Historic SiteLava Beds National MonumentSunset Crater Volcano National MonumentCabrillo National MonumentFort McHenry National Monument and Historic ShrineLewis and Clark National Historical ParkTheodore Roosevelt National ParkCanaveral National SeashoreFort Pulaski National MonumentLittle Bighorn Battlefield National MonumentThomas Edison National Historical ParkCanyonlands National ParkFort Sumter and Fort Moultrie National Historical ParkLower East Side Tenement Museum National Historic SiteTonto National MonumentCape Cod National SeashoreFort Vancouver National Historic SiteMesa Verde National ParkTumacácori National Historical ParkCapitol Reef National ParkGlacier National ParkMontezuma Castle National MonumentTuzigoot National MonumentCapulin Volcano National MonumentGlen Canyon National Recreation AreaMount Rainier National ParkValles Caldera National PreserveCastillo de San Marcos National MonumentGolden Spike National Historical ParkNatural Bridges National MonumentVanderbilt Mansion National Historic SiteCedar Breaks National MonumentGrand Canyon National ParkOlympic National ParkVicksburg National Military ParkChaco Culture National Historical ParkGrand Teton National ParkOrgan Pipe Cactus National MonumentWalnut Canyon National MonumentChattahoochee River National Recreation AreaGreat Falls ParkPadre Island National SeashoreWhiskeytown National Recreation AreaChesapeake & Ohio Canal National Historical ParkGreat Sand Dunes National Park & PreservePerry's Victory & International Peace MemorialWhite Sands National ParkChickamauga & Chattanooga National Military ParkGuadalupe Mountains National ParkPetrified Forest National ParkWright Brothers National MemorialChristiansted National Historic SiteGulf Islands National SeashorePictured Rocks National LakeshoreWupatki National MonumentColonial National Historical ParkHaleakalā National ParkPinnacles National ParkYellowstone National ParkColorado National MonumentHarpers Ferry National Historical ParkPipe Spring National MonumentYorktown Battlefield Part of Colonial National Historical ParkCrater Lake National ParkHawaiʻi Volcanoes National ParkPrince William Forest ParkYosemite National ParkCraters Of The Moon National Monument & PreserveHistoric Jamestowne Part of Colonial National Historical ParkPuʻuhonua o Hōnaunau National Historical ParkZion National ParkCumberland Island National SeashoreHome Of Franklin D Roosevelt National Historic SiteRio Grande Wild & Scenic River

Some of these parks may require reservations, including a parking pass. You'll want to check the requirements for the park you're visiting before heading out.

Why do some national parks charge entrance fees?

While it’s true that your federal income taxes do, in a way, fund the National Park Service, your contributions are relatively small in comparison to the agency’s needs. Entrance fees are used to “enhance visitor experience” under the Federal Lands Recreation Enhancement Act.

“At least 80 percent of funding from recreation fees stays in the park where it is collected, and the other 20 percent is used to benefit parks that do not collect fees or parks which generate only a small amount of revenue,” the National Park Service explains.

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Fees are established based on a structure the agency uses that “simplifies and standardizes entrance fees across parks of similar types.” Rocky Mountain and Zion, for example, are both large and well-visited parks that have park-specific annual passes of $70, a per-vehicle fee of $35, a per-person fee of $20, and a per-motorcycle fee of $30.

Many parks also explain how they use the entrance fee funds. At Death Valley, for example, revenue from entrance fees has been used to design Braille park brochures, repair damages at a beloved feature, and support custodians and emergency medical services.

Source: The Hill - News