The intrusion of colonial rule at the dawn of the 20th century gave rise to economically-motivated internal migrations of young persons from the rural areas of Owerri Province to other parts of Eastern Nigeria from 1915-1965. Population pressure and adverse ecological conditions in the source area were the major causes of the out-migrations; while the destinations were the emerging urban centers and the agricultural-fertile parts of Eastern Nigeria, which hosted the migrant tenant farmers. Although the out-migrations led to urban and socio-economic growth of Eastern Nigeria during the period, nonetheless, it had adverse effects on agricultural productivity in the source area. Thus, the study made proactive recommendations aimed to curtail the out-migrations, which is still a recurring decimal in this part of Nigeria and throughout the Global South.