Colorado Statehood: August 1, 1876, and the State Flag

Colorado became the 38th state on August 1, 1876. President Ulysses S. Grant issued the proclamation admitting it to the Union. Its birthday falls in the same year as the United States' centennial, which explains the nickname Centennial State. The familiar red-C state flag came later, in 1911.

Colorado state flag with a red C and gold disk over blue and white horizontal stripes.
FORTISVEX catalog illustration of the modern Colorado state flag. The flag design is separate from the statehood date.

When is Colorado's state birthday?

Colorado's statehood anniversary is August 1. This date marks admission to the United States, not the beginning of Colorado's human history or the adoption of its modern flag. The Library of Congress's August 1 history connects the 1876 admission with the national centennial year.

From territory to the 38th state

Colorado Territory was established on February 28, 1861. Congress passed an enabling act on March 3, 1875, opening the way for a state constitution and admission. According to the Colorado General Assembly, voters approved the constitution on July 1, 1876. It took effect when Colorado became a state a month later.

The U.S. Senate's Colorado timeline records Grant's August 1 proclamation. Keep the two 1876 dates separate: July 1 was the vote on Colorado's state constitution; August 1 was admission to the Union. Neither was an original-state ratification of the U.S. Constitution.

Why is Colorado called the Centennial State?

Colorado joined the Union in 1876, one hundred years after the Declaration of Independence. The nickname refers to that centennial year. It does not mean Colorado became a state on July 4.

When was the Colorado flag adopted?

The legislature adopted the red-C flag on June 5, 1911. Its three horizontal bands are blue, white and blue, with a red C surrounding a golden disk. The Colorado State Archives also records later refinements: the red and blue were standardized in 1929, and the C's size and position were clarified in 1964.

That timeline matters for historical displays. A modern Colorado flag can represent the state at an anniversary celebration, but it should not be captioned as a flag used at the 1876 admission. Label a modern illustration by its actual design and explain the older event separately.

Colorado statehood at a glance

  • Statehood: August 1, 1876.
  • Order of admission: 38th state.
  • Nickname connection: Admission during America's centennial year.
  • Red-C flag adopted: June 5, 1911.

Explore Colorado flags and other state birthdays

For a statehood display, compare the sizes, materials and mounting options in our Colorado state flag collection. For more anniversary dates, visit the U.S. state birthday calendar.

Sources and further reading

Oct 24th 2026 Sydney S.

Recent Posts