Prior to the 20th century, classical liberalism was the dominant political philosophy in the United States. It was the political philosophy of Thomas Jefferson and the signers of the Declaration of Independence and it permeates the Declaration of Independence, the Constitution, the Federalist Papers and many other documents produced by the people who created the American system of government.
Many of the emancipationists who opposed slavery were essentially classical liberals, as were the suffragettes, who fought for equal rights for women. Basically, classical liberalism is the belief in liberty. Even today, one of the clearest statements of this philosophy is found in Jefferson's Declaration of Independence. At that time, as is the case today, most people believed that rights came from government. People thought they only had such rights as government elected to give them. But following the British philosopher John Locke, Jefferson argued that it's the other way around. People have rights apart from government, as part of their nature. Further, people can form governments and dissolve them. The only legitimate purpose of government is to protect these rights.
People who call themselves classical liberals today tend to have the basic view of rights and role of government that Jefferson and his contemporaries had. Moreover, they do not tend to make any important distinction between economic liberties and civil liberties.
On the left of the political spectrum, things are more complicated. The major difference between 19th century liberals and 20th century liberals is that the former believed in economic liberties and the latter did not.
Twentieth century liberals believed that it is not a violation of any fundamental right for government to regulate where people work, when they work, the wages they work for, what they can buy, what they can sell, the price they can sell it for, etc. In the economic sphere, then, almost anything goes.