Gold rush was the biggest reason why people of Europe came to USA. Firstly, the conditions in Europe were bad in the XIX's century. So with the gold rush, the Europeans came to USA to try their self in it. So there is the first consequence: It was a goal that almost immigrants 'd like to find.
Then, the second one is that the migrants lost all their money. So the gold rush wasn't what they expected : Instead of making them rich, it made them poorest than they were.
Hope it helps
