These documents are based on my lecture notes for Drexel courses Economics 201, 202, 211, and 212: Principles of Economics, in two slightly different forms. The lecture notes cover most of the topics I try to cover in class, and a few that I sometimes don't get around to in some sections. It is, in any case, a personal choice and expression of the topics. Of course, this is not a finished textbook (and perhaps it will never be finished). I am gratified if the notes are useful in their present form, despite these caveats!
Essential Principles of Economics is now in the process of being updated, a process that will take some time. Revised chapters will supercede the old chapters as they are available. The revised chapter outline, with indications of chapters that have been updated, is below; old version chapter numbers may not agree with this list. Roger A. McCain