Answer:
I am sorry but some one deleted my answer it is the discovery of gold It wasn’t until 1859, however, that white settlers would finally start pouring in to the Rocky Mountains. Gold had been discovered, and now, fortune-seekers traveled to what was then mainly part of Kansas Territory to make their fortune, claiming “Pikes Peak or Bust.” Two years later, as the population grew, the area became Colorado Territory. Maybe now they won't delete it however I hope this helps you
Step-by-step explanation: