What is the name of the most dangerous fault line in the U. S.?
Your

Hayward fault

While the San Andreas fault gets much of the attention, it's the Hayward fault that quake experts consider the most dangerous fault in America.

Explanation:

answer; in the united states the plains include the great plains of the west and the tail grass prairie to the south of the great lakes extending east to the appalachian plateau

answerthe above statement is correct(true)