What did the marshall court interpret the necessary and prper clause to mean?

His case is important because it contains 2 important principles 
1) THE PRINCIPLE OF IMPLIED POWERS: the court greatly expanded what the constitution allows the central government to do. Today, congress has many ''implied powers'' that allow it to make laws that are ''necessary and proper'' to carry out its listed powers. 
2) THE PRINCIPLE OF NATIONAL SUPREMACY: The federal Constitution and federal laws come before the constitutions and laws of the states. When the federal government is using powers that belong to it, the states must give away 
THE SUPREME COURT INTERPRET THE '' NECESSARY AND PROPER'' CLAUSE by binding the judges in every states, even if the states law conflicts with the constitution

Transcontinental railroad was the most effective way to travel.