All national parks, including Utah's Arches, Bryce, Canyonlands, Capitol Reef and Zion, will be free for the day.
Camping and overnight fees and timed entrance reservations at select parks still apply.
Wednesday will be the third fee-free day of the year.
Guests can experience the national parks for free Aug. 4 for the anniversary of the Great American Outdoors Act, Sept. 28 for National Public Lands Day and Nov. 11 in honor of Veterans Day.
