The U.S. state known for its wild west history is Wyoming. It played a significant role in the expansion of the American frontier, featuring iconic sites such as Yellowstone National Park, which was the first national park in the U.S. The state has numerous historical landmarks, including the Oregon Trail and remnants of pioneer settlements. Wyoming is also known for its rodeos, cowboy culture, and vast landscapes of mountains and plains, embodying the spirit of the wild west.