For 18 short months, a group of riders carried letters from St. Joseph, Missouri, to Sacramento, California, and they did it in just 10 days. Crossing 1,800 miles of rough western terrain, at breakneck speeds, the Ponny Express tied the east to the west in ways that would become pivotal in the years to come.

On today's episode of America's National Parks Podcast, the Pony Express National Historic Trail and the riders who have become synonymous with the American West.