May 1, 1890: Female Zookeeper Opens Elitch's Zoological Gardens

Female zookeeper Mary Elitch opens Elitch’s Zoological Gardens, making her the first woman in history to own and operate a zoo. No other zoos existed west of Chicago at the time, and in an era when women had little political or economic power, the idea of a female zookeeper running the show was extraordinary.
Mary Elitch and her husband, John Elitch Jr., had previously opened a restaurant together called Elitch Palace Dining Room, then bought a nearby farm to grow fruits and vegetables to serve customers. A lifelong animal lover, Mary Elitch began caring for stray animals at the farm. She imagined one day transforming the farm into a zoo with exotic animals, apples orchards, gardens, and entertainment.
That dream became a reality on May 1st, 1890, when she opened Elitch’s Zoological Gardens. The attraction was an overwhelming success. Elitch would go on to wow visitors with outdoor symphony concerts and stage shows by the biggest legends of the time.
May 13, 1859: Clear Creek Gold Discovery Ignites "Gregory Fever"

Prospector John Gregory, credited with igniting the Colorado Gold Rush after discovering gold at Black Hawk in January 1859, makes another big discovery at the North Fork of Clear Creek.
His discovery couldn’t have come at a better time. The gold mining region of Colorado was experiencing whiplash from a rapid boom and bust cycle that saw tens of thousands of disappointed prospectors giving up and returning east. Denver alone had lost two-thirds of its people.
When Gregory presented a vial of gold containing his new diggings, valued at eighty dollars, everything changed. The Colorado Gold Rush was reinvigorated. Prospectors began pouring in, filling up mining camps, and tearing the landscape apart with excitement so intense, it became known as “Gregory Fever.”
May 27, 1941: Construction Begins on Denver Ordnances Plant

The first steel frames of Denver’s Ordnances Plant are erected in the Jefferson County farmlands west of the city. Five months earlier, the federal government granted Denver the contract for the munitions plant. This created thousands of jobs and spurred an ambitious effort to construct a complex with over 200 buildings and a major manufacturing area in a matter of months.
Remington Arms, operator of the plant, would become one of the largest producers of ammunition in the US for World War II, with the Denver Ordnances Plant producing millions of rounds of ammunition per day. At the conclusion of the war, the plant’s operations ceased, though the complex still stands to this day, providing office, laboratory, and storage facilities for various governmental agencies.
May 30, 1894: Massive Flood Decimates Boulder

Rapid snowfall melt and 96 hours of heavy rain flood Boulder in what is considered the area’s first 100 year flood. As Boulder Creek swelled out of its banks, a rampage of surging waters tore through the area. It destroyed roads and bridges, wiped out communities, and decimated Boulder’s infrastructure. The damage was so extensive the area was cut off from the rest of Colorado for five days. In reporting on the event, Boulder’s newspaper, the Daily Camera, wrote, “The Windows of Heaven Opened and Boulder Was Submerged.”
Once the floodwaters receded, the landscape of Boulder County was permanently reshaped. Many said the natural beauty of Boulder Canyon was never the same. While downtown Boulder eventually recovered, some surrounding communities and mining camps were never rebuilt, having been washed away entirely.