Answer:
Insanely quick population growth, 'boomtowns', and mining agreements.
Step-by-step explanation:
Boomtowns were cities that held huge populations in a few months, due to the Gold Rush, these Boomtowns allowed merchants to sell their products easily, since no one could compete with their goods. Levi Straus, a German inventor, created Levi pants, sturdy mining pants that quickly became popular.
Hope this helps! :)