The U.S. Constitution is specific about some features of the relationship between national and state governments and vague about other features. What would be an example of how vague provisions have helped Americans adapt the constitution to changing times?
Perhaps the best example of a vague provision in the Constitution being used to adapt to changing times is the Commerce Clause. The Commerce Clause is an example of both a specific and a vague provision and its use has changed over the years.
The Commerce Clause is very specific in that it says that only Congress may make laws that regulate commerce between the states. There is no wiggle room there that would allow states to regulate commerce between them. However, what is really not made clear is what constitutes interstate commerce. This is a vague provision that has been used to adapt the Constitution to changing times.
One clear example of this came in the 1960s when the Congress used the Commerce Clause to ban racial discrimination. Although the Supreme Court had banned official segregation in 1954, it had not banned discrimination by private parties. Congress did this in the Civil Rights Act of 1964. What Congress said was that all kinds of businesses like restaurants and hotels were involved in interstate commerce. Therefore, the Congress was within its rights to ban discrimination in those establishments. By doing so, it was simply regulating interstate commerce.
Thus, Congress used the vagueness (are restaurants in one town really part of interstate commerce) to update the Constitution to ban racial discrimination.