From the Dec. 29, 2015, Yahoo! News "Country's largest national parks hit visitor records" by Felicia Fonseca, AP.
Grand Canyon, Yellowstone and Zion set visitation records for 2015.
The National Park service celebrates its 100th anniversary in 2016 and even bigger crowds are expected.
They are on track to attract 300 million visitors for 2015 in all the parks. This will be last year's record of 293 million.
Not counting the month of December, the Grand Canyon has had 5.3 million, Zion 3.5 million and Yellowstone 4.1 million.