If you really want to understand what the word, "liberal," means in the context of American politics, this is the stuff to read, and yes, in American politics, "liberal" has meant "left" for a long time. Deal.
Reading list on the meaning of liberalism in American politics
If you really want to understand what the word, "liberal," means in the context of American politics, this is the stuff to read, and yes, in American politics, "liberal" has meant "left" for a long time. Deal.