While not known by many, Picacho Peak is actually older than the mountains to the east, the Organ Mountains. Picacho Peak is over 9 million years old! Picacho Peak was a well known location along the Butterfield Trail, a trail that carried passengers and U.S. Mail between St. Louis and San Francisco, which operated from 1857 to 1861. Mesilla was approximately halfway between those two locations. Contrary to common belief, the peak was never an active volcano.
Battle of Picacho Pass/Peak - Westernmost battle of the American Civil War. Occurred on April 15th, 1862