What is the phrase national supremacy and how this affects state and local governments?

What is the phrase national supremacy and how this affects state and local governments?
The federal system that the United States uses divides power between the states and their creation called the national government. As a way to glue the states together and ensure a level playing field, the Constitution includes the Supremacy Clause (Article Four, paragraph Two). It says the Constitution is the supreme law of the land. In any dispute, the Constitution wins by definition. The challenge lies in knowing where to draw the line between states merely exercising their reserved powers and violating the Constitution.

In your initial post, explain to us in your own words about at least four things, policy areas, that have traditionally been the domain of states under the Tenth Amendment.

In an additional paragraph identify at least one landmark Supreme Court ruling that applied the Constitution and national supremacy to a constitutional challenge to a state’s laws of policy. What was the outcome?

In your reply posts to at least two different classmates about their posts and cases, assess the rulings and the impact that the rulings they identified had on society. Further, write a one-paragraph “opinion” of your own in which you use the Constitution as the basis of either your concurring opinion or your dissent from what the majority of the Justices wrote in that case.

In all three (or more) of your posts, cite the sources of your information in proper APA format.