The mining boom began with the a) invention of dynamite by Alfred Nobel
b) discovery of the Comstock Lode
c) passage of the Homestead Act

probally   a few days after there called

in the 1800s, chinese workers migrated to the united states, first to work in the gold mines, but also to take agricultural jobs, and factory work, especially in the garment industry. chinese immigrants were particularly instrumental in building railroads in the american west, and as chinese laborers grew successful in the united states, a number of them became entrepreneurs in their own right. as the numbers of chinese laborers increased, so did the strength of anti-chinese sentiment among other workers in the american economy. this finally resulted in legislation that aimed to limit future immigration of chinese workers to the united states, and threatened to sour diplomatic relations between the united states and china.

soviet influence spread across eastern europe sharply during and after wwii. the soviet armies liberated the countries in eastern europe and occupied them from the germans as they were forced to retreat towards germany.