THE 75TH ANNIVERSARY of the AIEE is a particularly appropriate occasion to review and take stock of the developments in power transmission. A corresponding review by Prof. H. J. Ryan just 25 years ago traced the development of power transmission from its early beginnings and discussed how, among other things, the number of phases and the system frequency were chosen. At that time, the 800-mile 287.5-kv line from Hoover Dam to Los Angeles, Calif., was just being erected. The newly solved problem of lightning, system stability, and symmetrical components were still being digested and assimilated. The a-c calculating board had just been adopted and accepted as a tool for the solution of regulation, load, and reactive power flow and stability problems. The closely allied problem of synchronous machine transient analysis had also just completed its first great bound in understanding.