The state of Montana was once home to a massive inland sea that covered much of North America around 80 million years ago during the Late Cretaceous period.
Treasure County is a county located in the state of Montana in the northwestern United States. It was established on February 7, 1919, and takes its name from the surrounding area's reputation as a treasure trove of mineral resources. The county's rich history dates back long before its official establishment, with evidence of Native American presence in the area dating back thousands of years.

During the late 19th century, the discovery of gold and other valuable minerals brought a wave of prospectors and settlers to Treasure County. The region experienced a mining boom, and towns such as Mystic and Coalwood sprang up to support the mining operations. However, these towns saw a decline in population and economic activity as the mining industry waned in the early 20th century.

In the early years, agriculture played an important role in the county's economy, with ranching and farming becoming the mainstay for many residents. Cattle ranching, in particular, remains a significant component of Treasure County's agricultural industry to this day. The county's fertile soils and favorable climate also support the cultivation of various crops, including wheat, barley, and hay.

Since its establishment, Treasure County has had a small and close-knit community. With a sparse population spread out across its vast landscapes, the county offers a rural and tranquil lifestyle. Today, it continues to embrace its natural beauty and agricultural heritage while also attracting outdoor enthusiasts who appreciate its abundance of recreational opportunities, including hunting, fishing, and camping.

This timeline provides a glimpse into the major events and milestones that have shaped the history of Treasure County, Montana.

  • 1864: Treasure County is established.
  • 1876: The town of Hysham is founded.
  • 1881: The first post office is established in Hysham.
  • 1919: The Montana Legislature establishes the county seat in Hysham.
  • 1920: The county courthouse is built in Hysham.
  • 1922: Treasure County High School is built in Hysham.
  • 1933: The first bridge across the Yellowstone River is constructed.
  • 1968: The coal mine in Sanders begins operations.
  • 1970: The county population reaches its peak at over 1,500.
  • 1984: The coal mine in Sanders closes, leading to a significant decline in population.
  • 1993: The town of Bighorn is incorporated.