Disparities between member states are considerable, but the largest economic disparities in the EU are to be found within the borders of member states. In other words, the problem of cohesion is most evident at the regional level. Disparities between the richest and poorest regions are quite pronounced. The richest regions have approximately four times the GDP per head of the poorest regions. As a dimension of EU policy the term cohesion originated in the Single European Act of 1986 and was born out of a concern that moves towards greater economic integration would favour the relatively advanced countries and regions of the EU.