Explain the actions of Americans during the “Manifest Destiny” Era

After the last expansion, gold was discovered at Sutter's' Mill, bringing many more Americans from the East, and benefitting them greatly, even bringing in people from outside America. This revolutionized America's economy. Manifest Destiny brought money, land, resources, and a strengthened economy to the Americans

Explanation:

In the 19th century US, Manifest Destiny was a belief that was widely held that the destiny of American settlers was to expand and move across the continent to spread their traditions and their institutions, while at the same time enlightening more primitive nations.

i think it would be reparing roads  

the answer to your question is:

strong-mayor system