Commissioner Zenzinger: Celebrating the Sesquisemiquincentennial

If you are looking for a true 24-letter mouthful to liven up your summer vocabulary, try pronouncing this word: Sesquisemiquincentennial.

This unique, official term is a blend of two massive milestones happening at the exact same time: the United States Semiquincentennial (America 250) and the Colorado Sesquicentennial (Colorado 150). While it is often called the "250-150" celebration for short, here in Jefferson County, we are fully embracing the historic weight of this dual anniversary. To honor these milestones, the Jefferson County Commissioners officially presented the America 250-Colorado 150 Proclamation earlier this year on January 5, 2026. This proclamation kicked off a year-long effort by the Jefferson County Historical Commission (JCHC) to preserve, celebrate, and share our deep-rooted local history.

Before Colorado officially achieved statehood in 1876, the people and places of Jefferson County were already shaping the future of the American West. This year, we are paying special tribute to that foundational era through several landmark initiatives:

• Sesquicentennial Colorado Site Awards: The JCHC has carefully selected historic properties from every region of Jefferson County to receive this special recognition. Each site holds local, state, or national significance, having been built and actively used before 1876. This designation is strictly honorary, carries no property restrictions, and relies entirely on voluntary owner participation.
• Recognizing Foundational Towns: Our non-profit partner, History Jeffco, is leading a dedicated effort to recognize and highlight the foundational towns that served as the bedrock of our county's early economy and community life.

The culmination of these historical celebrations will take place this autumn at our annual awards ceremony.

• October Ceremony: The upcoming Hall of Fame (HOF) Award Ceremony in October will be entirely dedicated to the theme of America 250—Colorado 150.
• Lifetime Achievement Award: A brand-new Lifetime Achievement Award has been added to the ceremony specifically to honor individuals who have made monumental contributions to preserving Colorado's heritage.
• Site Recognition: The newly selected Sesquicentennial Colorado Sites will be formally recognized and celebrated during this HOF event.

We invite every resident to explore the stories of the people and places that made Jefferson County what it is today through several multimedia platforms as well:

• Historically Jeffco Magazine: Keep an eye out for this year's issue, themed "Jeffco Celebrates America 250—Colorado 150," which features a comprehensive special section dedicated entirely to our dual anniversaries. The 2026 issue will be published later this year and will be available on the Historically Jeffco Magazine webpage. 
• YouTube Video Symposium: The JCHC is producing a video symposium for YouTube that will take viewers on a visual tour of several recognized Sesquicentennial Colorado sites.
• Social Media Education: Throughout the year, the JCHC’s Facebook and YouTube channels are posting historical information, event updates, and interactive links to connect the public with local historical organizations.

As your Jefferson County Commissioners, we encourage you to follow along on social media, read the latest historical articles, and join us in celebrating 150 years of Colorado pride and 250 years of American history right here in Jefferson County.

- Rachel

Commissioner Zenzinger can be reached via email.

Visit the Jefferson County Commissioners webpage to learn more about the commissioners.