The data were gathered from literature and by correspondence. Of 47 states having deer, 30 register over-population trouble; only the southeast is free from excess deer. All 3 types (whitetail, mule, and Columbian blacktail) exhibit irruptive behavior, culminating at its worst in starvation of the deer and decline of browse food plants. Irruptions are of recent origin, and differ from ordinary winter die-offs. Although some departures occur in local cases, the sequence of events is frequently as follows: distress in inferior browse; consumption of worthless browse; malnutrition, disease and parasites; distortion of age-classes corresponding to fawn die-offs; starvation of adult deer and range based on carrying capacity. The causes of irruptions are mainly predator-control, buck laws, loggings, and forest fire. About a decade after the inauguration of fire control and the cessation of logging, there is often a closure of tree crowns which reduces the supply of browse and the carrying capacity of the range. Deer are socially tolerant and therefore do not disperse when over-abundant, as other species do. In the past, predatqr attack frequently forced deer to scatter. Mild winters, artificial feeding, and downed tops from logging often postpone, but never prevent, the ultimate shrinkage of both the herd and its range. The malnutrition which follows large-scale consumption of inferior browse causes a deterioration in both wt. and antler development. Only about 1/10 of the known problem areas are reported as stabilized as of 1945. Most of the remedial reductions have been too late, too light, or too intermittent to accomplish their purpose.