Paralleling the extensive growth and expansion of interconnected electric power systems in the United States and Canada during the past 60 years, has been the related need to regulate generation in the constituent areas, and the power flow between them, to achieve equitable, reliable and economic system and area operation. Many individuals and groups have made contributions to these objectives. These contributions constitute the evolution of the system and area realtime control art from modest, tentative beginnings to the comprehensive, broadly scoped and highly capable present day on-line digital control systems. This paper presents one individual's view, based largely on personal experience and observation, of significant steps in this evolutionary process. The paper deals primarily with the analog phases of these developments, many of the philosophies and techniques of which remain basic to current digital executions.