CHEYENNE, Wyo. (AP) - National parks in the U.S. will sharply drop the number of days they allow visitors to get in for free.

After waiving entrance fees for 16 days in 2016 and 10 days in 2017, the National Park Service announced Tuesday that it will have four no-cost days next year.

They will be Martin Luther King Jr. Day (Jan. 15), the first day of National Park Week (April 21), National Public Lands Day (Sept. 22) and Veterans Day (Nov. 11).

It comes after the Park Service said it was considering raising vehicle entry fees at 17 busy parks mainly in the West, including Denali, Yellowstone, Grand Canyon, Yosemite and Zion.

The proposal would raise the cost from $25 or $30 per week to $70.

The agency estimates the increase would generate an additional $70 million to help address backlogged maintenance and infrastructure projects.

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