America practices a mixed republican form of Government which is in contrary to pure Direct Democracy.
America is a Constitutional Federal Republic which means, constitution is upheld to be supreme. Federal means giving equal powers and rights to the states to execute laws. And Republic means that public vote for legislative representatives and these officials form the Government.
Democracy and Republicanism are the major and important concepts of Liberalism. That’s the reason two major parties were named Democrats and Republicans. Some states have the power to enact laws, bring forth legislation, voted on a particular law and even recall the election which shows that America follows democracy. So we can call American a mixed Republican Constitution with high democratic values.