The official spin is that America is a democracy. It's a crucial part of the national mythology. Well, guess what: This is nowhere near the truth. The Founders never said they were setting up a democracy. In fact, in The Federalist, three of them argued repeatedly against democracy. The republic the Framers set up with their 1787 Constitution was intended to be an electoral oligarchy. What else would you expect from a constitution that originally gave slavemasters extra votes representing 3/5 of each of their slaves?
On the other hand, there is a lot of democracy below the federal level: in most states and localities, direct democracy has been implemented in the form of initiative, referendum, and recall. It's not quite as participatory as the Athenian assembly, in which all the citizens met every month or week to do what legislatures and city councils do today, but it's actually far more democratic than the US federal government, which restricts democratic participation to electing a limited number of officials and was far more restrictive in its unamended original version.
Naturally, there's a huge contradiction that is undermining the entire creaky 18th-century American system. On the one hand, you have the oligarchic federal government which has over the decades become increasingly monarchic. On the other, there's the long-term trend toward democratization which has led to the universal right to vote and to expanding civil rights for women, racial minorities, gays and lesbians, and immigrants among others. The democratic trend also involves the expansion of the vote until now all adult citizens can vote, where originally only propertied white males were eligible. Increasingly, these two opposite trends are working against each other. Eventually they will not be able to coexist, and one or the other must prevail at the other's expense. At that time, a revolution will be highly likely. That time will be when the colonial conquest campaign in the Middle East is lost and the troops come home.
The 1787 Constitution is obsolete. There might be a way to save it: state nullification, the right of any one state to veto or nullify any federal law, regulation, and decree. Thomas Jefferson himself came up with that, and insisted that it was the only thing that would ultimately prevent the American republic from degenerating into a tyranny. Now would be a good time to revive the idea. It would make an excellent 28th Amendment. Otherwise, it would be a good idea to scrap the dysfunctional federal system entirely, and replace the current 1787 Constitution with something at least as good at protecting rights but far more democratic.
The problem with an oligarchic constitution, you see, is that an oligarchy ultimately loses touch with the mass of ordinary citizens. Oligarchs are unaccountable to the people. Increasingly drunk on power, they lose touch with reality as well. In the democratic age, good government requires the rulers to be accountable to the citizens, or they will rule arbitrarily and tyrannically. So a modern constitution must make the government accountable. That means democracy in some form. Some critics of the current constitution advocate a European-style parliamentary system elected through proportional representation instead of the current setup. What was originally the equality of the executive and legislative branches has degenerated into the monarchic supremacy of the executive, or "Imperial Presidency". European-style parliaments subordinate the executive (usually called a "prime minster") to the legislature. This may be more workable. However, it still proves oligarchic in practice if it doesn't have at least some features of direct democracy (initiative, referendum, recall, nullification). But we won't know what we'll come up with till the revolution begins and the Fourth Republic is born.