Railroads transformed time travel. What other modern inventions transformed time and travel like the railroads did?

Why are nation-states difficult to create?

Which of the following quotes from the constitution describes the senate? "no person…who shall not have attained to the age of twenty five years, and been seven years a citizen of the united states, and who shall not, when elected, be an inhabitant of that state in which he shall be chosen." "the…shall chose their other officers, and also a president pro tempore, in the absence of the vice president, or when he shall exercise the office of president of the united states.""the…shall be composed of members chosen every second year by the people of the several states.""the…shall choose their speaker and other officers; and shall have the sole power of impeachment."

After studying the timeline above, what observations can you make about u.s. environmental policy between 1970 and 1996?