Final answer:
Following gold discovery at Sutter's Mill, the migrants to California were known as forty-niners and this event marked the beginning of the California Gold Rush.
Step-by-step explanation:
After gold was discovered at Sutter's Mill, migration to California rose and these people were known as forty-niners. This rapid influx of miners and others seeking wealth led to the California Gold Rush. It wasn't only the prospectors who congregated in California; the arrival of merchants, saloonkeepers, and others who wanted to profit from the booming economy quickly followed. Many towns sprung up as a result of the gold discovery, with San Francisco experiencing explosive growth from a few hundred residents to thousands in a short time.