Frederick taylor is known best for what concept that improves efficiency in manufacturing

to protect the united states' role as a world leader, president truman wanted to prevent the soviet union from spreading communism beyond its post-world war ii boundaries. he declared that the united states must assist any nations struggling to prevent a communist takeover.

the completion of the erie canal spurred the first great westward movement of american settlers, gave access to the rich land and resources west of the appalachians and made new york the preeminent commercial city in the united states.