New Delhi, Oct. 29 -- There are breathtaking differences in the scale of economic activity across and within the states of India, and policymakers need to address this unequal geography.

Among the major states, the two richest, Goa and Gujarat, have per capita incomes 10 times and six times that of Bihar, respectively. The top ranked five states account for as much as 50% of India's total gross domestic product (GDP) while the bottom five account for only about 10%.

In exports, the top ranked three states-Gujarat, Maharashtra and Tamil Nadu-account for 55% of total exports. The 10 states ranked at the bottom account for less than half-a-percent each.

In investment projects, just three states-Maharashtra, Gujarat and Karnataka-account f...