I am rather slow to find out all that is bot good and available on the internet. Case in point is my finding just last night that an entire course of lectures by Murray Rothbard on American Economic History from the Civil War through World War II. The course is entitled "The American Economy and the End of Laissez-Faire: 1879-World War II" and was taught by Rothbard while he held a position at Brooklyn Polytechnic in 1986. All of them have been made available by the Ludwig von Mises Institute and are free for the listening.
The first lecture is called "The Civil War and Its Legacy" and is presented here with much gratitude.