I would argue that the biggest problem facing our country today is a lack of good jobs and/or a lack of people to fill what good jobs there are.
In the past, there were pretty good jobs for almost everyone. A person who never went to college could work in a factory and make good money. A person who went to college could be pretty secure for life. Nowadays, with globalization and increased competition, this is no longer true. We do not seem to know how to make good jobs, particularly for blue collar workers with relatively little education. This contributes to a situation in which we have inequality of wealth and in which our economy stagnates. We need to in some way encourage more innovation and entrepreneurship that could create better jobs for a broader variety of people.