December 10, 1910
Herold China and Pottery Company incorporated by John J. Herold. Becomes Coors Porcelain in the 1920s, Coors Ceramics in 1986, and CoorsTek in the 2000s.
December 14, 1910
Leyden Coal Mine fire disaster when ten miners are killed and several more injured. Shaft Number 2 is destroyed but mine is able to rebuild.
Town of Westminster incorporated.
May 10, 1911
Concert by renowned opera singer Mary Garden puts Red Rocks Amphitheatre on the world musical map.
September 7, 1911
Standley Lake formally dedicated by U.S Secretary of Agriculture James Wilson.
Passage of the Mountain Parks Charter Amendment when Denver voters approve a one-half mill levy property tax to fund Denver Mountain Parks. Genesee Park, the largest mountain park, is acquired.
July 6, 1912
Lookout Mountain Funicular completed with two cars that seat 32 people. The railroad is abandoned upon completion of the Lariat Trail.
August 2, 1912
Two shot and South Platte Hotel destroyed when gunman/arsonist terrorizes South Platte. Hotel is later rebuilt.
- Castle Rock Mountain Railway funicular begins operation carrying tourists to a dance hall and casino on top of Castle Rock on South Table Mountain
- The four-story National Guard Armory building, made from local cobblestones (possibly the largest cobblestone building in the country), is built in Golden
- The Adolph Coors Company is incorporated
- Foss Drug is established in Golden
- Adolph Coors becomes president of Herold China and Pottery Company (later becomes CoorsTek)
April 15, 1913
Colorado Legislature passes an act authorizing the city of Denver to establish the Denver Mountain Parks in the mountain areas of Jefferson, Clear Creek, and Grand Counties.
May 17, 1913
Charles Quaintance opens dance pavilion and light tower on South Table Mountain. He also cuts a road up the mountain, offering tourists donkey rides to the top of Castle Rock.
December 4 & 5, 1913
Blizzard of 1913 dumps 4 to 5 feet of snow in Golden, Arvada, Morrison, and Evergreen, the largest 24 hour and overall storm amounts on record for Jefferson County. The death of pioneer resident John Bergen in Evergreen and the probable death of Golden dairyman John Klaassens are attributed to the storm.
The Lariat Trail, also known as the Lariat Loop Road, to Lookout Mountain Park at the top of Lookout Mountain completed by William “Cement Bill” Williams.
George Turner begins building Turnerville, the precursor of Tiny Town, a miniature town for children, on the location of the Denver-Leadville Stage Coach Station. Originally built to entertain his young daughter, Turnerville grows large enough to open to the public in 1920.
Prohibition goes into effect. Coors Brewery dumps its entire stock of beer (about 17,000 gallons) into Clear Creek. The Brewery adapts by making a non-alcoholic beer called Mannah and malted milk.
Lorraine Lodge (now Jefferson County's Boettcher Mansion), Charles Boettcher's summer home on Lookout Mountain, completed. Designed by Denver architects Fisher and Fisher, the Arts and Crafts-style home was given to Jefferson County by Boettcher's granddaughter, Charline Breeden, in 1972; it is now open to the public for tours and special events.
June 3, 1917
Buffalo Bill, who died January 10, 1917, is buried on top of Lookout Mountain near the current site of the Pahaska Tepee, built in 1921 as his museum. 20,000 mourners attend.
Work completed on the Grand Chief Hosa Lodge in Genesee Park. Designed by Jules Jacques Benois Benedict.
1918 to 1919
Spanish influenza epidemic hits Jefferson County, hospitalizing hundreds and claiming lives including Golden City Councilor Oscar Nolin and pharmacist Henry Foss. All public meetings and assemblies are banned.
August 10, 1919
First airplane to fly over Golden flies over Genesee Mountain and drops a wreath on Buffalo Bill's grave.