Important issues

These are issues important to the future of the U.S., and by extension, the world. The solutions that I'd call for would require new legislation and various types of reform.

Critical

These are the most critical issues, that really need something done soon. In roughly the order of importance, as I see it:

Money's entanglement in politics

Money (usually in the form of campaign contributions) should not be able to buy votes, directly or indirectly.

Energy and the environment

There is an imminent environmental catastrophe—due to climate change, which is in turn due to use of carbon-based fuels—that will cause disruption of just about all infrastructure in the world. Energy use needs to either move away from carbon fuels, or find a way to use them with much less impact on the environment (atmosphere).

Health care

All humans should have equal access to health care, regardless of income. The health insurance system in the U.S. makes this impossible, and needs to be reformed.

Education

The education system needs to be rethought some. Instead of teaching facts, students should be learning analytical skills in school (aside from just math and high school chemistry). Real social sciences should be introduced (as is being done with Linguistics in parts of Washington state), and ways should be found for students to interact with primary literature (i.e., read, understand, discuss, find flaws with, and be able to answer questions about any text that they have the background to read, including basic scientific texts in just about any field).