Both indicators are associated initially with increasing and subsequently with declining levels of emigration, corresponding to the inverted U-curve relationship. Both indicators also have an overall positive effect on immigration. Development in poor countries will help incomes grow, enabling people exiting poverty to cover migration costs, therefore these countries will initially see rising levels of emigration. Eventually, once countries reach a certain level of development and are able to bridge the income gaps, migration levels will start declining again. Caution should therefore be used in concluding definitively that all countries have had or will follow the described path.