The Lewis and Clark Expedition passed through Montana in 1805-1806, on their journey to explore the western portion of the United States. They traveled up the Missouri River and crossed the Rocky Mountains, encountering many Native American tribes and documenting the flora and fauna of the region.
Located in the southern part of the state, Big Horn County in Montana has a rich and diverse history that stretches back thousands of years. The land was initially inhabited by various Native American tribes, including the Crow and Shoshone people, who relied on the area's natural resources for their sustenance and way of life. European settlers began arriving in the mid-1800s, with the establishment of the Montana Territory in 1864.

The discovery of gold in the 1860s brought an influx of miners to the area, leading to the establishment of several mining camps and towns. However, it was the railroad that truly transformed the county, providing a vital transportation link and facilitating trade and development. The completion of the Northern Pacific Railroad through Big Horn County in 1882 further accelerated the region's growth and brought new opportunities.

Agriculture played a significant role in the county's development, with large-scale farming and ranching becoming prevalent. Cattle ranching, in particular, thrived in the vast grasslands of Big Horn County, contributing to the local economy and way of life. The town of Hardin emerged as a key commercial and administrative center, serving as the county seat and providing essential services to the surrounding rural communities.

Over the years, Big Horn County has faced its share of challenges and transformations. The decline of mining and changes in agricultural practices have led to shifts in the local economy. Nevertheless, the county remains a resilient and vibrant community, with a thriving tourism industry focused on its natural beauty and cultural heritage. From its Native American roots to the bustling settlements of the late 19th century, Big Horn County's history is a testament to the resilience and adaptability of its inhabitants.

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

  • 1865: The area that would later become Big Horn County is explored by Captain William Clark of the Lewis and Clark Expedition.
  • 1851: The Fort Laramie Treaty is signed, establishing Native American reservation lands in the area.
  • 1871: The first settlers arrive in the area.
  • 1886: Big Horn County is officially established.
  • 1907: The town of Hardin is incorporated as the county seat.
  • 1910: The Chicago, Burlington and Quincy Railroad reaches Hardin, stimulating growth and development in the county.
  • 1930s: During the Great Depression, the Fort Custer Army Air Base is established near Hardin, bringing economic opportunities to the county.
  • 1962: The Yellowtail Dam is completed on the Bighorn River, providing irrigation and hydroelectric power to the area.
  • 2009: The Big Horn County Historical Museum is opened, showcasing the county's rich history.