Answer:
The Supremacy Clause of Article VI (6) of the US Constitution declares the Constitution, as well as federal laws and treaties made in accordance with the Constitution are the supreme law of the land. In lay terms, this means that the Constitution, federal laws and treaties can overrule state and local laws.
Article VI, Clause 2 (Supremacy Clause)
This Constitution, and the laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the Constitution or laws of any State to the contrary notwithstanding.