The Colorado gold rush A.K.A the Pikes Peak gold rush was one of the largest ones in US history. Tens of thousands of miners flooded the area looking for quick money. This massive immigration led to the creation of many cities and the state of Colorado, which was a part of Kansas and Nebraska.
Many of the founded cities during the gold rush became ghost towns but some of them remained like Denver. This is due to many reasons. The quantity of the easy-to-reach gold decreased drastically. Moreover, gold was discovered in California.