At the present time, plants in the 100 to 500 Mw size range are more numerous and carry the greatest portion (over 50%) of the total steam-electric plant load in the US utillties industry. The contribution of plants of over 1,000-Mw capacity is increasing more rapidly than any other size classification and at present represents about 10% of the total capacity. By 1962 the TVA will have six plants with capacities of over 1,000-Mw. The largest steam-electric plant in the US is the TVA plant at Kingston, Tenn., with a nameplate capacity of 1,440Mw. Turbine-generator wits are also following a trend of ever-increasing size. In present construction, the 150 to 200 Mw size range for units ls the most common and represents the greatest contribution to capacity. Two units of 500-Mw nameplate rating each, the largest in the US, are on order by the TVA, and an 80 Mw unit is contemplated. (auth)