What is the supreme law of the land?

What does this answer mean?

The answer is the U.S. Constitution. It sets up the federal government, divides power among Congress, the president, and the courts, and protects basic rights. Calling it the supreme law of the land means no other law can go against it.

That phrase comes from the Constitution itself. Article VI says the Constitution, the federal laws made under it, and treaties are the supreme law, and that judges in every state are bound by them. When a state law or a federal law conflicts with the Constitution, the Constitution comes first.

Delegates meeting in Philadelphia signed the Constitution on September 17, 1787. Today that date is Constitution Day and Citizenship Day, set by federal law to honor the Constitution and everyone who has become a citizen, whether by coming of age or by naturalization. The Constitution can only be changed through amendments, and it has 27 of them.

This is one of the 20 questions on the 65/20 list, so applicants who qualify for that special consideration study it too.