As the “American experiment” continues into the 21st century, what are some of the problems and challenges that have arisen that the Founders did not contemplate when writing the Constitution?

The United States Constitution was written in 1791. The world from which this document arose is drastically different from the world we live in today. Technological advances, societal changes, and shifting demographics have led to a United States that would be unrecognizable to the Founders today. As the “American experiment” continues into the 21st century, what are some of the problems and challenges that have arisen that the Founders did not contemplate when writing the Constitution?