Keystone Resort is officially over the hill.

The resort will celebrate its 40th anniversary today. Coincidentally, the North and South Bowls will open Saturday – the earliest opening ever for the bowls. The Outback had its earliest opening Friday, as well, and Keystone now has 1,321 skiable acres open.

As if the early openings of the North, South and Outback bowls weren’t enough, Keystone is offering $40 lift tickets to celebrate the conclusion of its fourth decade of existence. The families of the original founders – Bill Bergman and Max Dercum – will hand out doughnuts as part of the festivities, and patrons can pick up original trail maps from 1970.

When Keystone opened to the public 40 years ago, it became the third ski area in Summit County, and lift tickets cost only $5.

The year was 1970, the same year President Richard Nixon signed a bill allowing 18-year olds to vote, Jimi Hendrix died, a plane carrying the Wichita State football team crashed in Colorado and Colorado State College changed its name to University of Northern Colorado.

The resort’s inaugural season brought 75,000 skiers to Keystone. Last year Keystone had 981,000 skier visits – an increase of more than 1,300 percent.

A number of significant events have befallen Keystone over the past 40 years. Patrol director Craig Simson – a 20-year employee of Keystone – said the most significant event in his two decades of service was the 1997 merger that brought Keystone under the ownership of Vail Resorts.

“Everything changed when Vail Resorts took over and really started to throw a lot of money and financing toward the ski area and help us improve all the facilities and the lifts,” Simson said.

He said the addition of the Area 51 terrain park – ranked No. 2 in the country by TransWorld magazine – was another significant event.

“I joke that it all started with a picnic table, but that’s actually true,” Simson said. “Some employees were doing tricks off the table, and the idea for A51 came from that.”

Keystone’s major events over the past 40 years:

•1970 – Keystone opens as the third ski resort in Summit County.

•1972 – The resort’s first snowmaking system is installed, making Keystone among the first in Colorado to offer man-made snow.

•1974 – Ralston Purina – yes, the pet food company – acquires Keystone and invests $20 million in capital improvements.

•1980 – The Ranch Course opens as Keystone’s first 18-hole championship golf course.

•1984 – Keystone adds its first gondola along with 12 new runs and two triple-chair lifts.

•1985 – Night skiing opens at Keystone.

•1989 – The $10 million Keystone Conference Center opens as the largest conference facility in the Colorado Rockies.

•1991 – Keystone’s second gondola opens, providing access from Keystone Mountain (now Dercum Mountain) to the top of North Peak.

•1994 – The $700 million base area at river run is developed by Keystone Real Estate Developments – a joint venture between Ralston Purina and Intrawest.

•1996 – Keystone finally allows snowboarding, making if one of the last holdouts.

•1997 – Vail Resorts is formed when Keystone and Breckenridge ski resorts merge with Vail and Beaver Creek ski resorts to form the largest resort company in North America.

•2003 – Area 51 terrain park opens and quickly becomes recognized as one of the top parks in the country.

•2010 – Vail Resorts adds EpicMix to Keystone to track skier and snowborder on-mountain statistics.

Vail Resorts hasn’t said much about future capital improvements to Keystone Resort, but Keystone spokesman Ryan Whaley said the resort will continue its mission to become the most family-friendly ski resort in the country.

“Our focus is completely on family,” Whaley said. “That’s why we offer our Kidtopia Festivals during the busiest times of the season.”

Adventure Point on top of Dercum Mountain offers a host of family-friendly offerings, including the massive Snow Fort that will open Christmas Day. There’s also one of Colorado’s longest, steepest tubing hills, snowbiking, snowshoeing and a host of other family-oriented activities.

This year Keystone added a warming hut and restrooms at the mid-station where 3- to 6-year-olds take lessons. Before, learners had to ride the gondola up or down to hit the head or raise their body temperature.

Finally, operation of a hybrid bus began this season to transport families between the villages and resorts to the base area. The bus stays on the Keystone side of Highway 6, but Whaley said it will make navigation and transportation easier for guests.

SDN reporter Drew Andersen can be contacted at (970) 668-4633 or drewa@summitdaily.com.