The paper begins with a review of the purpose of governing in interconnected power systems, and the disparity between recorded governing response routinely observed on large electric utility power systems and the ideal governing response that is used in most planning studies. It describes recordings and analyses that AEP (USA) has made in recent years, which offer quantitative insight into the nature and causes of the governing response observed in the Eastern Interconnection (EI) of the United States and Canada. The AEP measurements, simulations of system governing response to a unit trip with comparisons to recordings made of the event and cost analyses of governing margin are used with observations of system governing responses to provide a basis for conclusions and observations. The paper includes some consideration of changes arising from the present restructuring of the utility business to a market-driven system and the impact of decisions on the need to monitor and manage reliability performance of key equipment and overall system performance under the new open, yet more fragmented structure.